Kidney stone matrix proteins:Role in stone formation

Stone formation is induced by an increased level of urine crystallization promoters and reduced levels of its inhibitors.Crystallization inhibitors include citrate,magnesium,zinc,and organic compounds such as glycosaminoglycans.In the urine,there are various proteins,such as uromodulin(Tamm-Horsfall protein),calgranulin,osteopontin,bikunin,and nephrocalcin,that are present in the stone matrix.The presence of several carboxyl groups in these macromolecules reduces calcium oxalate monohydrate crystal adhesion to the urinary epithelium and could potentially protect against lithiasis.Proteins are the most abundant component of kidney stone matrix,and their presence may reflect the process of stone formation.Many recent studies have explored the proteomics of urinary stones.Among the stone matrix proteins,the most frequently identified were uromodulin,S100 proteins(calgranulins A and B),osteopontin,and several other proteins typically engaged in inflammation and immune response.The normal level and structure of these macromolecules may constitute protection against calcium salt formation.Paradoxically,most of them may act as both promoters and inhibitors depending on circumstances.Many of these proteins have other functions in modulating oxidative stress,immune function,and inflammation that could also influence stone formation.Yet,the role of these kidney stone matrix proteins needs to be established through more studies comparing urinary stone proteomics between stone formers and non-stone formers.

Comparisons of voided urine cytology, nuclear matrix protein-22 and bladder tumor associated antigen tests for bladder cancer of geriatric male patients in Taiwan, China

Aim： To compare the results of bladder tumor associated antigen （BTA TRAK）, nuclear matrix protein 22 （NMP 22） and voided urine cytology （VUC） in detecting bladder cancer. Methods： A total of 135 elderly male and 50 healthy volunteers enrolled in this study were classified into three groups： （i） 93 patients with bladder cancer; （ii） 42 patients with urinary benign conditions; and （iii） 50 healthy volunteers. BTA TRAK and NMP 22 kits were used to detect bladder cancer. Voided urine cytology was used to compare the sensitivity and specificity of the screening tests. Results： The sensitivity and specificity of cytology, BTA TRAK and NMP 22 were 24% and 97%, 51% and 73%, 78% and 73%, respectively. The level of NMP 22 increased with tumor grading. The BTA TRAK kit has the lowest sensitivity among the screening tests. The NMP 22 with the best sensitivity can be an adjunct to cytology for evaluating bladder cancer. Conclusion： The NMP 22 test has a better correlation with the grading of the bladder cancer than BTA TRAK. As cytology units are typically not available in hospitals or in outpatient clinics, NMP 22 might be a promising tool for screening bladder cancer.

Association between serum cartilage oligomeric matrix protein and coronary artery calcification in maintenance hemodialysis patients

Background Coronary artery calcification(CAC)is common in end-stage renal disease(ESRD)patients,and the extent of CAC is closely related to cardiovascular outcomes in ESRD patients.Cartilage oligomeric matrix protein(COMP),as a component of the vascular matrix,has been found to be an inhibitor of arterial calcification in basic studies.However,there is no clinical research on the correlation between COMP and CAC in maintenance hemodialysis(MHD)patients.The aim of this study was to explore the relationship between serum COMP levels and CAC and cardiovascular events in MHD patients.Methods Serum COMP levels were compared between 54 MHD patients and 66 healthy people.MHD patients were then divided into three groups according to the tertiles of the concentration of COMP level and were followed up for major adverse cardiac events(MACEs),which were defined as a combined end point of new onset angina pectoris,nonfatal myocardial infarction,heart failure,coronary artery revascularization,hospitalization due to angina pectoris and all-cause deaths.The CAC score was calculated based on computed tomography scans.Results The serum COMP level in MHD patients was significantly higher than that in the general population[984.23(248.43-1902.61)ng/mL vs.219.01(97.26-821.92)ng/mL,P<0.01].Serum COMP levels were positively correlated with CAC(r=0.313,P=0.021)and serum parathyroid hormone in MHD patients(r=0.359,P<0.01).Linear regression suggested that after adjusting for age,fasting blood glucose(Glu)and glycosylated hemoglobin(HbAlc),CAC score was an independent predictor in the final model for COMP level(β=0.424,t=3.130,P<0.01).The receiver operating characteristic(ROC)curve showed that COMP≥994 mg/mL had 68.0%sensitivity and 72.4%specificity for the prediction of severe CAC[area under the curve(AUC):0.674,P=0.030,95%CI:0.526-0.882].After a median follow-up of 16 months(8-24 months),there was no difference in the incidence rate of MACEs between the upper,middle and lower serum COMP groups.Conclusions Our study found that MHD patients have higher levels of circulating COMP than controls.The serum COMP level is positively correlated with CAC score and could be used as a biomarker of severe CAC in MHD patients.However,there is no obvious correlation between serum COMP levels and the incidence of cardiovascular events.

Dentin matrix protein 1 and phosphate homeostasis are critical for postnatal pulp, dentin and enamel formation

Deletion or mutation of dentin matrix protein 1 （DMP1） leads to hypophosphatemic rickets and defects within the dentin. However, it is largely unknown if this pathological change is a direct role of DMP1 or an indirect role of phosphate （Pi） or both. It has also been previously shown that Klotho-deficient mice, which displayed a high Pi level due to a failure of Pi excretion, causes mild defects in the dentinal structure. This study was to address the distinct roles of DMP1 and Pi homeostasis in cell differentiation, apoptosis and mineralization of dentin and enamel. Our working hypothesis was that a stable Pi homeostasis is critical for postnatal tooth formation, and that DMP1 has an antiapoptotic role in both amelogenesis and dentinogenesis. To test this hypothesis, Dmpl-null （Dmpl-/-）, Klotho-deficient （kl/kl）, Dmpl/Klotho-double-deficient （Dmpl-/-/kl/kl） and wild-type （WT） mice were killed at the age of 6 weeks. Combinations of X-ray, microcomputed tomography （I^CT）, scanning electron microscopy （SEM）, histology, apoptosis and immunohistochemical methods were used for characterization of dentin, enamel and pulp structures in these mutant mice. Our results showed that Dmpl-/- （a low Pi level） or kl/kl（a high Pi level） mice displayed mild dentin defects such as thin dentin and a reduction of dentin tubules. Neither deficient mouse line exhibited any apparent changes in enamel or pulp structure. However, the double-deficient mice （a high Pi level） displayed severe defects in dentin and enamel structures, including loss of dentinal tubules and enamel prisms, as well as unexpected ectopic ossification within the pulp root canal. TUNEL assay showed a sharp increase in apoptotic cells in ameloblasts and odontoblasts. Based on the above findings, we conclude that DMP1 has a protective role for odontoblasts and ameloblasts in a pro-apoptotic environment （a high Pi level）.

Induction of Bone Matrix Protein Expression by Native Bone Matrix Proteins in C2C12 Culture

Objective To study the expression of bone matrix protein （BMP） induced by bovine bone morphogenetic proteins （BMPs） in vitro. Methods Type 1 collagen, osteopontin （OPN）, osteonectin （ON）, osteocalcin （OC）, and bone sialoprotein （BSP） were detected by immunohistochemistry in C2C12 cultured from day 1 to day 28. Results The signaling of bone matrix protein expression became weaker except for type I collagen, OC and BSP after 5 days. Fourteen days after culture, the positive signaling of type I collagen, OPN, ON, OC, and BSP was gradually declined, and could be detected significantly as compared with that of the negative control on day 28. BMP assay showed that the lkaline phosphatase （ALP） activity was higher in C2C12 culture than in the control during the 14-day culture. Also, total protein and DNA significantly increased during the 14-day culture. High levels of ALP were seen in preosteoblasts and osteoblsts in vivo and in differentiating osteoblasts in vitro. ALP was well recognized as a marker reflecting osteoblastic activity. Conclusion Native bovine BMP induces conversion of myoblasts into osteoblasts, produces type I collagen, and plays significantly role in osteoinduction and bone matrix mineralization of C2C 12 in vitro.

CHANGES OF NUCLEAR MATRIX PROTEIN AND ITS RELATIONSHIP WITH c-erbB-2 IN HUMAN COLON ADENOCARCINOMA

Objective： Nuclear matrix protein is tissue, cell-type specific, and tumor-relative. It plays an important role in the regulation of intranuclear processes. Some researches also showed that a c-erbB-2 promoter-specific DNA-binding nuclear matrix protein is present only in malignant human breast tissues and induces mitogenesis and cell surface expression of the c-erbB-2 protein in resting NIH/3T3 cells. But it is not clear that how it in colon adenocarcinomas. Methods： Two-dimensional gel electrophoretic method was used for NMP identification and immunohistochemistry was used for c-erbB-2 detection in 12 cases of colon adenocarcinomas and matched adjacent normal colon tissues. Results： 5 different nuclear matrix proteins （named C1-C5） were identified in 12 colon adenocarcinoma specimens, but not in the matched adjacent normal colon tissues; 3 nuclear matrix proteins （named N1-N3） were identified in all 12 matched adjacent normal colon tissues, but not in colon adenocarcinoma specimens. A nuclear matrix protein （named N4） was detected in all of 9 moderated-well differentiated adenocarcinomas and all 12 matched adjacent normal colon tissues, but not in 3 poor-differentiated adenocarcinomas. All of the 10 colon adenocarcinomas which had the nuclear matrix protein C4 were c-erbB-2 expression positive. Conclusion： The data suggest that there are specific nuclear matrix proteins in colon adenocarcinomas and its subtypes, which maybe valuable to serve as markers of colon adenocarcinomas in future. Nuclear matrix protein C4 probably is a c-erbB-2 promotor-specific nuclear matrix protein in colon adenocarcinomas, and may induce the expression of c-erbB-2.

NUCLEAR MATRIX PROTEIN IN LEUKEMIA CELLS

Objective: To compare the composition of nuclear matrix proteins (NMP) between leukemia cells and normal bone marrow cells. Methods: NMP was isolated by high-salt extraction and identified in acute and chronic myelogenous leukemia cells as well as in the blast phase of chronic leukemia. On SDS-PAGE, NMPs with molecular myelogenous ferment from what were seen in normal bone marrow cells were present in both acute and chronic myelogenous leukemia. Conclusion: Marked changes of NMP, not only in contents but also in compositions, exist in leukemic cells compared with normal bone marrow cells. NMP may serve as a target of chemotherapeutic drug against leukemia.

Changes of β_3 Integrins and Extracellular Matrix Proteins in the Endometrium of Unexplained Infertility

The purpose of this study was to investigate changes of β 3 integrins and extra cellular matrix proteins including fibronectin (FN), laminin (LN) and collagen type Ⅳ (CL typeⅣ) on the endometrium of secretory phase from 31 fertile women (fertility group)and 34 women with unexplained infertility (infertility group) by a histochemical method.The results were as follows:In glandular epithelium, β 3 integrin appeared in the mid secretory phase and continued to late secretory phase in the fertility group, but was not expressed during the secretory phase in the infertility group. Extracellular matrix proteins from the fertility group were expressed more strongly in mid secretory phase than that in the early secretory phase, and were weakest in the late secretory phase. Compared with the fertility group, the levels of extracellular matrix proteins in the infertility group were elevated in the secretory phase. In conclusion: our current study demonstrate that β 3 integrin and extracellular matrix proteins are expressed at different levels in the endometrium during the menstrual cycle. They are involved in endometrial changes during the menstrual cycle and during the implantation of the blastocyst. Their unusual expression result in the failure of implantation.

Anti-nuclear matrix protein 2+ juvenile dermatomyositis with severe skin ulcer and infection: A case report and literature review

BACKGROUND Juvenile dermatomyositis(JDM)is an idiopathic inflammatory myopathy that occurs in childhood.It is characterized by muscle weakness and a characteristic rash.Previous literature reports have rarely described JDM with severe skin ulcers and infections.CASE SUMMARY Herein,we describe a case of a 2-year-old female patient who suffered from JDM,whose myositis-specific autoantibodies were positive for anti-nuclear matrix protein 2 antibody,with progressively worsening skin ulcers and severe infections.The patient was treated with glucocorticoids and various immunosuppressants.Nevertheless,further progression of the disease and the combination of primary disease and severe infection in the later period were fatal.CONCLUSION In children,anti-nuclear matrix protein 2+JDM combined with skin ulcers often indicates severe disease.In such cases,personalized treatment for the primary disease and infection prevention and control are essential.

弹状病毒基质蛋白(Matrix protein)的研究进展

弹状病毒的基因组由1段线性单股不分节的负链RNA组成,主要编码5个结构蛋白,分别为核蛋白(Nucleoprotein,N)、磷蛋白(Phosphoprotein,P)、基质蛋白(Matrix protein,M)、糖蛋白(Glycoprotein,G)和RNA聚合酶(RNA polymerase,L)。其中,基质蛋白(M)是一种多功能性蛋白,在病毒的侵染过程中参与病毒粒子的出芽、装配,抑制核质运输,调控宿主的基因转录,诱导细胞凋亡等。本文综述M蛋白的研究进展。

Altered serum level of cartilage oligomeric matrix protein and its association with coronary calcification in patients with coronary heart disease

BackgroundCartilage oligomeric 矩阵蛋白质(COMP ) 主要在骨胳的系统和脉管的光滑的肌肉房间被发现。最近的研究证明它在血容器上有保护的功能并且能也禁止脉管的石灰化。我们在冠的心疾病( CHD )调查了浆液 COMP 病人，并且在浆液 COMP 和首先经历了多片跟随的冠的 angiography 的 233 个连续的胸疼痛病人全部的冠的 artery.MethodsA 的石灰化之间的关系在六个月以内计算了断层摄影术( MSCT )被招募并且根据缩小百分比的冠的 angiography 钠直径划分了成二个组：CHD 组(缩小 50% 的直径， n = 194 ) 并且控制组(直径变窄 <50% ， n = 39 ) 。Gensini 分数，句法分数和冠的动脉钙分数(CAC ) 是计算的。浆液 COMP 水平用 COMP 的 ELISA.ResultsThe 层次被决定比在控制组在 CHD 组是显著地更高的 155.7 (124.5-194.5 ) ng/mL 对 128.4 (113.0-159.9 ) ng/mL， P = 0.019。在 COMP， Gensini 分数，句法分数，冠的狭窄的严厉和有狭窄的冠的动脉的数字之间没有关联 >50% 。浆液 COMP 与年龄被相关(r = 0.294， P < 0.001 ) ， fasting 葡萄糖(r = 0.163， P = 0.015 ) ， HbA1c (r = 0.194， P = 0.015 ) 并且 CAC (r = 0.137， P = 0.037 ) 。逐步的线性回归分析显示出那 COMP 水平，年龄是在 CHD 病人的 CAC 的独立预言者(= 0.402， t = 2.612， P = 0.015；= 0.472， t = 3.077， P = 0.005 ) 。为预言 CHD 的 COMP 的性能在曲线(AUC ) 下面作为区域被显示出：0.632， 95% CI：0.549-0.715 和上面的 tertile CAC 是 AUC：0.602， 95% CI：在操作冠的动脉的特征(巨鸟) 曲线 analysis.ConclusionCalcification 的接收装置的 0.526-0.678 是浆液 COMP 的一个独立预言者。

Altered profiles of nuclear matrix proteins during the differentiation of human gastric mucous adenocarcinoma MGc80-3 cells

AIM: To find and identify specific nuclear matrix proteins associated with proliferation and differentiation of carcinoma cells, which will be potential markers for cancer diagnosis and targets in cancer therapy.METHODS: Nuclear matrix proteins were selectively extracted from MGc80-3 cells treated with or without hexamethylamine bisacetamide (HMBA), and subjected to 2-D gel electrophoresis. The resulted protein patterns were analyzed by Melanie software. Spots of nuclear matrix proteins differentially expressed were excised and subjected to in situ digestion with trypsin. Peptide masses were obtained by matrix-assisted laser-desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) analysis and submitted for database searching using Mascot tool.RESULTS: The MGc80-3 cells were induced into differentiation by HMBA. There were 22 protein spots which changed remarkably in the nuclear matrix, from differentiation of MGc80-3 cells compared to control.Eleven of which were identified. Seven proteins -actin, prohibitin, porin 31HL, heterogeneous nuclear ribonucleoprotein A2/B1, vimentin, ATP synthase, and heatshock protein 60 were downregulated, whereas three proteins - heat shock protein gp96, heat shock protein 90-beta, and valosin-containing protein were upregulated,and the oxygen-regulated protein was only found in the differentiated MGc80-3 cells.CONCLUSION: The induced differentiation of carcinoma cells is accompanied by the changes of nuclear matrix proteins. Further characterization of those proteins will show the mechanism of cellular proliferation and differentiation, as well as cancer differentiation.

Alreration of nuclear matrix-intermediate filament system and differential expression of nuclear matrix proteins during human hepatocarcinoma cell differentiation

AIM:To investigate the association between the configurational and compositional changes of nuclear matrix and the differentiation of carcinoma cells. METHODS: Cells cultured with or without 5 x 10"3 mmol/L of hexamethylene bisacetamide (HMBA) on Nickel grids were treated by selective extraction and prepared for whole mount observation under electron microscopy. The samples were examined under transmission electron microscope. Nuclear matrix proteins were selectively extracted and subjected to subcellular proteomics study. The protein expression patterns were analyzed by PDQuest software. Spots of differentially expressed nuclear matrix proteins were excised and subjected to in situ digestion with trypsin. The peptides were analyzed by matrix-assisted laser-desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS). Data were submitted for database searching using Mascot tool (www.matrixscience.com). RESULTS: The nuclear matrix (NM) and intermediate filament (IF) in SMMC-7721 hepatocarcinoma cells were found relatively sparse and arranged irregularly. The nuclear lamina was non-uniform,and two kinds of filaments were not tightly connected. After induction for differentiation by HMBA,the NM-IF filaments were concentrated and distributed uniformly. The heterogeneous population of filaments,including highly branched utrathin filaments could also be seen in the regular meshwork. The connection between the two kinds of filaments and the relatively thin,condensed and sharply demarcated lamina composed of intermediate-sized filaments was relatively fastened. Meanwhile,21 NM proteins changed remarkably during SMMC-7721 cell differentiation. Four proteins,i.e. mutant Pyst1,hypothetical protein,nucleophosminl,and LBP were downregulated,whereas four other proteins,eIF6,p44 subunit,(3-tubulin,and SIN3B were upregulated with the last one,SR2/ASF found only in the differentiated SMMC-7721 cells. CONCLUSION: The induced differentiation of SMMC-7721 cells by HMBA is accompanied by the configurational changes of nuclear matrix-intermediate filament (NM-IF) system and the compositional changes of nuclear matrix protein expression. These changes may be important morphological or functional indications of the cancer cell reversion.

Nectin-like Molecule 1 Inhibits the Migration and Invasion of U251 Glioma Cells by Regulating the Expression of An Extracellular Matrix Protein Osteopontin

Objective To investigate the molecular mechanism of nectin-like molecule 1(NECL1) inhibiting the migration and invasion of U251 glioma cells.Methods We infected U251 glioma cells with adeno-nectin-like molecule 1(Ad-NECL1) or empty adenovirus(Ad).Transwell and wound healing assays were performed to observe the migration of U251 cells incubated with the cell supernatant from Ad-NECL1 or Ad infected U251 cells.DNA microarray was applied to screen the gene expression profile after the restoration of NECL1 in U251 glioma cell lines.The differential expression of osteopontin(OPN),a gene related to migration and invasion,was further analyzed with semi-quantitative reverse transcription-polymerase chain reaction(RT-PCR),Western blot,and immunohistochemistry.Results The restoration of NECL1 inhibited migration of U251 cells significantly(P<0.05).Altogether 195 genes were found differentially expressed by microarray,in which 175 were up-regulated and 20 down-regulated,including 9 extracellular matrix proteins involved in the migration of cells.Both mRNA and protein expressions of OPN,the most markedly reduced extracellular matrix protein,were found decreased in U251 cells after restoration of NECL1.Immunohistochemical assay also detected an increase of OPN in glioma tissues,related with the progressing of malignant grade.Conclusion A link might exist between NECL1 and the extracellular matrix protein OPN in inhibiting the migration and invasion of U251 glioma cells.

Persistent elevation of fibrosis biomarker cartilage oligomeric matrix protein following hepatitis C virus eradication

Serum levels of cartilage oligomeric matrix protein(COMP) has been presented as a biomarker of liver fibrosis in several cross-sectional studies. COMP is also an essential mediator in carcinoma development and has also been associated with hepatocellular carcinoma. We present a prospective analysis of this biomarker in38 patients with chronic hepatitis C who were subject to eradication therapy with direct acting antivirals. We confirm previous studies associating COMP elevation with liver cirrhosis. We also show how viral levels are correlated with COMP at baseline. In our prospective analysis, we report that successful eradication of hepatitis C results in improvement in liver stiffness and laboratory liver function tests at 1 year follow-up. In contrast, median COMP-levels remain unchanged during the study period. We conclude that the biomarker potential of COMP in the prospective evaluation of liver diseases, remains to be elucidated.

Altered expression of nuclear matrix proteins in etoposide induced apoptosis in HL-60 cells

The events of cell death and the expression of nuclear matrix protein (NMP) have been investigated in a promyelocytic leukemic cell line HL-60 induced with etoposide. By means of TUNEL assay, the nuclei displayed a characteristic morphology change, and the amount of apoptotic cells increased early and reached maximun about 39% after treatment with etoposide for 2 h. Nucleosomal DNA fragmentation was observed after treatment for 4 h. The morphological change of HL-60 cells, thus, occurred earlier than the appearance of DNA ladder. Total nuclear matrix proteins were analyzed by 2-dimensional gel electrophoresis. Differential expression of 59 nuclear matrix proteins was found in 4 h etoposide treated cells. Western blotting was then performed on three nuclear matrix acssociated proteins, PML, HSC70 and NuMA. The expression of the suppressor PML protein and heat shock protein HSC70 were significantly upregulated after etoposide treatment, while NuMA, a nuclear mitotic apparatus protein, was down regulated. These results demonstrate that significant biochemical alterations in nuclear matrix proteins take place during the apoptotic process.

The 5'-flanking cis-acting elements of the human ε-globin gene associates with the nuclear matrix and binds to the nuclear matrix proteins

The nucleax mains attachment regions(MARs) and the binding nuclear matrix proteins in the 5’-flalildng cisacting elements of the humanε-globin gene have been examined. Using in vitro DNA-matrix binding assay,it has been shown that the positive stage-specific regulatory element (ε-PREII, -446bp-419bp) upstream of this gene could specifically associate with the nuclear matrix from K562 cells, indicating thatε-PREII mad be an erythroidspecilic facultstive MAR. In gel mobility shift assay and Southwestern blotting assal an eothroid-specific nuclear matrix protein (ε-NMPk) in K562 cells has been revealed to bind to this positive regulatory element (E-PREII). Furthermore, we demonstrated that the silencer (-392hp -177bp) uP8tream of the humanε-globin gene could associate with the nuclear matrices from K562, HEL and Raji cells. In addition, the nucleax matrix proteins prepared from these three cell lines could also bind to this silencer, suggesting that this silencer element linght be a constitutive nuclear mains attachment region (constitutive MAR). Our results demonstrated that the nucleax madrid and nuclear mains proteins lxilght play an important role in the regulation of the human 5-globin gene expression.

Fitting evolutionary process of matrix protein 2 family from influenza A virus using analytical solution of differential equation

The evolution of protein family is a process along the time course, thus any mathematical methods that can describe a process over time could be possible to describe an evolutionary process. In our previously concept-initiated study, we attempted to use the differential equation to describe the evolution of hemagglutinins from influenza A viruses, and to discuss various issues related to the building of differential equation. In this study, we attempted not only to use the differential equation to describe the evolution of matrix protein 2 family from influenza A virus, but also to use the analytical solution to fit its evolutionary process. The results showed that the fitting was possible and workable. The fitted model parameters provided a way to further determine the evolutionary dynamics and kinetics, a way to more precisely predict the time of occurrence of mutation, and a way to figure out the interaction between protein family and its environment.

STUDY ON NUCLEAR MATRIX PROTEINS FROM HUMAN BREAST CARCINOMA

Objective To investigate the marker protein of human breast carcinoma from nuclear matrix proteins (NMPs). Methods NMPs were injected subcutaneously into rabbit to get antiserum, which was used to detect the NMPs specificity for breast carcinoma. Results There was an apparent positive band (100 kD) in the NMPs of breast carcinoma, which did not exist in normal breast and other tumors that were detected.Conclusion One or one group of 100 kD NMPs were found to be related to human breast carcinoma, which may be involved in the carcinogenesis and development of human breast carcinoma and valuable for breast carcinoma diagnosis.

Intracellular Transport of HIV-1 Matrix Protein Associated with Viral RNA

HIV-1 matrix protein (MA) is a multifunctional structural protein localized on N terminus of Gag precursor p55. MA participates in HIV-1 assembly as membranotropic part of Gag precursor as well as an individual protein spliced from Gag early in infection. MA is found in the nuclei of infected cells and in plasma membrane, the site of virus assembly, in association with viral genome RNA. MA mutated variant M4 which contains two changed amino acids in N-terminal regions is also associated with viral RNA, but it is localized in the nuclear and cytoskeleton fractions but not in the plasma membrane suggesting that the mutant is deprived of membranotropic signal and “sticks” in the nuclei an d cytoskeleton, its previous location sites. These data allow suggesting that MA involved into transmission of viral RNA is transported to plasma membrane by cytoskeleton.