Objective: To reveal the special feature of calponin (CaP) on myosins of different states. Methods: Myosin phosphorylation determination, myosin Mg^(2+)-ATPase measurement and protein binding assay were used in this s...Objective: To reveal the special feature of calponin (CaP) on myosins of different states. Methods: Myosin phosphorylation determination, myosin Mg^(2+)-ATPase measurement and protein binding assay were used in this study. The lowest CaP/myosin ratio used in the assay was 1/10000(mol/mol), which was 10 thousands-fold lower than the CaP/myosin ratio used in previous studies. Results: In the absence of actin, micro-amount of calponin (MAC) stimulated the Mg^(2+)-ATPase activities of myosin in different states slightly but significantly; and more importantly, MAC significantly increased the precipitations of unphosphorylated myosin, Ca^(2+)-dependently and independently phosphorylated myosins by MLCK but not the myosin phosphorylated by PKA. Conclusion: MAC has a high efficient and selective effect on myosin in the absence of actin.展开更多
AIM: To study preliminarily the properties of myosin light chain kinase (MLCK) in rabbit liver.METHODS: The expression of MLCK was detected by reverse transcription-polymerase chain reaction (RT-PCR);the MLCK was obt...AIM: To study preliminarily the properties of myosin light chain kinase (MLCK) in rabbit liver.METHODS: The expression of MLCK was detected by reverse transcription-polymerase chain reaction (RT-PCR);the MLCK was obtained from rabbit liver, and its activity was analyzed by γ-32P incorporation technique to detect the phosphorylation of myosin light chain.RESULTS: MLCK was expressed in rabbit liver, and the activity of the enzyme was similar to rabbit smooth muscle MLCK, and calmodulin-dependent. When the concentration was 0.65 mg-L-1, the activity was at the highest level.CONCLUSION: MLCK expressed in rabbit liver may catalyze the phosphorylation of myosin light chain, which may play important roles in the regulation of hepatic cell functions.展开更多
Summary: To study whether there was an anti-cardiac myosin antibody (AMA) in serum of pa- tients with myocardial infarction (AMI), relationship between AMA and the prognosis in patients with AMI was investigated. In 6...Summary: To study whether there was an anti-cardiac myosin antibody (AMA) in serum of pa- tients with myocardial infarction (AMI), relationship between AMA and the prognosis in patients with AMI was investigated. In 67 patients with acute AMI, AMA was assayed by ELISA and left ventricular structure and cardiac function were examined by echocardiography at the end of the first week after infarction and during a 6-month follow-up. The patients with AMI were divided into AMA-positive group and AMA-negative group. The parameters of left ventricular end-dias- tolic function and prognosis were compared between the two groups. Results showed that the AMA was positive in 18 patients with AMI, with a positive rate of 26. 87 %, while it was negative in 20 health donors. The locations of myocardial infarction in the two groups were similar. There were significant differences in Killip class I (22. 22 % vs 55. 10 %, P<0. 05), decreasing of wall motion and ventricular aneurysm (92. 85 % vs 37. 5 %, P<0.01) between the positive group and the negative group. During a 6-month follow-up, the mortality was higher in AMA positive group than in AMA negative group (38. 89% vs 10. 20 %, P<0. 05). It is concluded that AMA can be detected in serum of patients with AMI and can serve as an important autoimmune marker. The autoimmune response might take place in AMI. AMA was associated with the left ventricular re- modeling and the prognosis of AMI.展开更多
Autoimmune is involved in the pathogenesis of ventricular remodeling in acute myocardial infarction (AMI).In the present study, we investigated the effect of anti-cardiac myosin heavy chain antibodies (AMHCA) from pat...Autoimmune is involved in the pathogenesis of ventricular remodeling in acute myocardial infarction (AMI).In the present study, we investigated the effect of anti-cardiac myosin heavy chain antibodies (AMHCA) from patients with AMI on rat cardiomyocyte apoptosis.Cardiomyocyte apoptosis was observed and measured by DNA end labeling and Annexin-Ⅴ/PI double-staining assay.The expression of apoptosis related p53 and Bcl-2 protein and the second messenger calcium were detected respectively by Western blotting, patch clamp and confocal calcium imaging.The results showed that AMHCA was able to induce cardiomyocyte apoptosis in a dose dependent manner.Apoptosis-accelerating nucleoprotein p53 was up-regulated, while apoptosis-inhibiting cytoplasmic protein Bcl-2 was down-regulated.In parallel, cytoplasmic calcium concentration was elevated.There was no effect on L-type calcium currents.It is concluded that AMHCA in patients with AMI as a novel triggering factor can induce cardiomyocyte apoptosis, which contributes to ventricular remodeling.展开更多
AIM: To identify and characterize the function of non-mu-scle myosin Ⅱ (NMM Ⅱ) isoforms in primary rat hepatic stellate cells (HSCs).METHODS: Primary HSCs were isolated from male Spra-gue-Dawley rats by pronase/coll...AIM: To identify and characterize the function of non-mu-scle myosin Ⅱ (NMM Ⅱ) isoforms in primary rat hepatic stellate cells (HSCs).METHODS: Primary HSCs were isolated from male Spra-gue-Dawley rats by pronase/collagenase digestion. Total RNA and protein were harvested from quiescent and culture-activated HSCs. NMM Ⅱ isoform (Ⅱ-A, Ⅱ-B and Ⅱ-C) gene and protein expression were measured by RealTime polymerase chain reaction and Western blot analyses respectively. NMM Ⅱ protein localization was visualized in vitro using immunocytochemical analysis. For in vivo assessment, liver tissue was harvested from bile duct-ligated (BDL) rats and NMM Ⅱisoform expression determined by immunohistochemistry. Using a selective myosin Ⅱ inhibitor and siRNA-mediated knockdown of each isoform, NMM Ⅱ functionality inprimary rat HSCs was determined by contraction and migration assays.RESULTS: NMM Ⅱ-A and Ⅱ-B mRNA expression was increased in culture-activated HSCs (Day 14) with sig-niflicant increases seen in all pairwise comparisons (Ⅱ-A: 12.67 ± 0.99 (quiescent) vs 17.36 ± 0.78 (Day 14), P < 0.05; Ⅱ-B: 4.94 ± 0.62 (quiescent) vs 13.90 ±0.85 (Day 14), P < 0.001). Protein expression exhibited similar expression patterns (Ⅱ-A: 1.87 ± 2.50 (quiescent) vs 58.64 ± 8.76 (Day 14), P < 0.05; Ⅱ-B: 1.17 ± 1.93 (quiescent) vs 103.71 ± 21.73 (Day 14), P < 0.05). No signif icant differences were observed in NMM Ⅱ-C mRNA and protein expression between quiescent and activated HSCs. In culture-activated HSCs, NMM Ⅱ-A and Ⅱ-B merged with F-actin at the cellular periphery and throughout cytoplasm respectively. In vitro stud-ies showed increased expression of NMM Ⅱ-B in HSCs activated by BDL compared to sham-operated animals. There were no apparent increases of NMM Ⅱ-A and Ⅱ-C protein expression in HSCs during hepatic BDL injury. To determine the contribution of NMM Ⅱ-A and Ⅱ-B to migration and contraction, NMM Ⅱ-A and Ⅱ-B expres-sion were downregulated with siRNA. NMM Ⅱ-A and/or Ⅱ-B siRNA inhibited HSC migration by approximately 25% compared to scramble siRNA-treated cells. Conversely, siRNA-mediated NMM Ⅱ-A and Ⅱ-B inhibition had no signif icant effect on HSC contraction; however, contraction was inhibited with the myosin Ⅱ inhibitor, blebbistatin (38.7% ± 1.9%).CONCLUSION: Increased expression of NMM Ⅱ-A and Ⅱ-B regulates HSC migration, while other myosin Ⅱclasses likely modulate contraction, contributing to development and severity of liver f ibrosis.展开更多
Actin and myosin were found to be associated with the cytoplasmic sleeve of plasmodesmata. As cytoskeletal proteins, actin and myosin are believed to regulate the conductivity of plasmodesmata (PDs) in higher plants...Actin and myosin were found to be associated with the cytoplasmic sleeve of plasmodesmata. As cytoskeletal proteins, actin and myosin are believed to regulate the conductivity of plasmodesmata (PDs) in higher plants. Using immunocytochemical methods, we found the two proteins to be co-localized - and closely linked to each other - in plasmodesmata and ectodesmata-like structure in ageing parenchymatous cells of Allium sativum L. We suggest that intercellular communication is affected by the interaction between actin and myosin.展开更多
Objective To study the effect of 4-6 weeks’ treadmill training of male SD rats on the contractile function of their gastrocnemius myosin heavy chain (MHC). Methods Forty male SD rats were randomly divided into contro...Objective To study the effect of 4-6 weeks’ treadmill training of male SD rats on the contractile function of their gastrocnemius myosin heavy chain (MHC). Methods Forty male SD rats were randomly divided into control group and training group. The treadmill training of the training group rats was incessantly performed for 4-6 weeks at an intensity of about 75% VO2max (18.5-24 m/min,gradient of 0°,each training session lasting 50 minutes,twice a day). The content of gastrocnemius MHC mRNA was tested by reverse transcription polymerase chain reaction (RT-PCR),and the changes of muscle fibre and its cross-section area (CSA) were measured using immunohistochemistry. Electric stimulation tests were used to determine the maximal tension of isometric contraction of the post-training gastrocnemius. Results ① After continuous treadmill training for 4-6 weeks,we found that the content of the total MHC,MHC Ⅰ,MHC Ⅱx,MHC Ⅱa mRNAs was 105%,105%,109% and 108% of that in the resting control group,respectively,and the MHC Ⅱb mRNA content did not change significantly. The percentage of MHC Ⅰ mRNA in the total MHC mRNA increased while that of MHC Ⅱ mRNA decreased after aerobic training. ② The slow type of fibre type Ⅰ was the main part of the MHC after training and the CSA of the muscle fibres increased simultaneously. ③ The maximal tension of isometric contraction by pulse stimulation of square wave in the training group increased significantly compared with that in the control group (P<0.01). Conclusion The findings indicate that aerobic exercise may promote an increase in the contractile function of MHC.展开更多
Experimental mice were immunized with cardiac myosin and complete Freunds adjuvant (CFA) on days 0, 7 and 30 and control mice were immunized with CFA. Sera and myocardium samples were harvested on days 15, 21 and 120...Experimental mice were immunized with cardiac myosin and complete Freunds adjuvant (CFA) on days 0, 7 and 30 and control mice were immunized with CFA. Sera and myocardium samples were harvested on days 15, 21 and 120 after the first immunization. Pathological findings demonstrated that there were necrosis and inflammatory infiltration in acute stage and fibrosis mainly in chronic stage of experimental group. Anti myosin antibodies were also found in sera of experimental mice, but not in control group. Our study showed that cardiac myosin served as an autoantigen to provoke autoimmunity and lead to the transformation of VMC into DCM.展开更多
Myostatin is a major factor involved in the regulation of skeletal muscle protein mass. High myostatin levels have been associated with an increase in myotube shrinkage. Enhanced myostatin expression is caused by pro-...Myostatin is a major factor involved in the regulation of skeletal muscle protein mass. High myostatin levels have been associated with an increase in myotube shrinkage. Enhanced myostatin expression is caused by pro-catabolic reactions involving compounds such as tumor necrosis factor (TNF)-α. The present study investigated the effects of agaro-oligosaccharides (AOSs) on hypercatabolism of myotubes exposed to TNF-α. C2C12 myotubes exposed to TNF-α in the presence or absence of AOSs. Myotube exposure to TNF-α resulted in a reduction in the amount of myosin heavy chain (MyHC) protein and a decrease in myotube diameter, which was associated with increased myostatin mRNA expression. AOSs prevented TNF-α-induced MyHC protein loss and restored normal myostatin mRNA levels, with agarobiose and agarotetraose effectively suppressing the hyperexpression of the mRNA. In addition, expression levels of the known myostatin inhibitors, latent transforming growth factor beta binding protein 3 (Ltbp3) and growth and differentiation factor-associated serum protein 1 (Gasp1) mRNAs, decreased more in TNF-α-induced myotubes than in the TNF-α-free control, possibly resulting in myostatin upregulation. However, AOSs restored nearly normal expression levels of Ltbp3 and Gasp1 mRNA, potentially suppressing myostatin expression. These findings suggest that AOSs could prevent myotube shrinkage induced by TNF-α.展开更多
Protein phosphorylation plays an important role in physiological processes, such as muscle contraction. Phospho-specific antibodies have become powerful tools to study these processes. Cardiac myosin binding protein-C...Protein phosphorylation plays an important role in physiological processes, such as muscle contraction. Phospho-specific antibodies have become powerful tools to study these processes. Cardiac myosin binding protein-C (cMyBP-C) is one of the proteins that make up the contractile apparatus of cardiomyocytes. Phosphorylation of cMyBP-C is essential for normal cardiac function, since dephosphorylation of this protein leads to its degradation and has been associated with cardiomyopathy. One of the upstream kinases, which phosphorylate cMyBP-C, is protein kinase D (PKD). While studying the role of PKD in cMyBP-C phosphorylation, we tried to analyze phosphorylation of PKD with a phospho-specific PKD-Ser744/748 antibody. Contrary to the expected 115 kDa, a signal was found for a 150-kDa protein. By MALDI-TOF mass spectrometry, we identified this protein to be cMyBP-C. These data were confirmed by immunostaining using the p-PKD-Ser744/748 antibody, which displayed a striated pattern similar to the one observed for a regular cMyBP-C antibody. To our knowledge there are no antibodies commercially available for phosphorylated cMyBP-C. Thus, the p-PKD-Ser744/748 antibody can accelerate research into the role of cMyBP-C phosphorylation in cardiomyocytes.展开更多
文摘Objective: To reveal the special feature of calponin (CaP) on myosins of different states. Methods: Myosin phosphorylation determination, myosin Mg^(2+)-ATPase measurement and protein binding assay were used in this study. The lowest CaP/myosin ratio used in the assay was 1/10000(mol/mol), which was 10 thousands-fold lower than the CaP/myosin ratio used in previous studies. Results: In the absence of actin, micro-amount of calponin (MAC) stimulated the Mg^(2+)-ATPase activities of myosin in different states slightly but significantly; and more importantly, MAC significantly increased the precipitations of unphosphorylated myosin, Ca^(2+)-dependently and independently phosphorylated myosins by MLCK but not the myosin phosphorylated by PKA. Conclusion: MAC has a high efficient and selective effect on myosin in the absence of actin.
基金Supported by the National Natural Science Foundation of China(39870324,YW)Key Innovation Project of Chinese Academy of Science,P.R.China(KSCX 2-2-01,XB Yao)Grant for Excellent Young Teachers of Ministry of Education of China(99044312,YW)
文摘AIM: To study preliminarily the properties of myosin light chain kinase (MLCK) in rabbit liver.METHODS: The expression of MLCK was detected by reverse transcription-polymerase chain reaction (RT-PCR);the MLCK was obtained from rabbit liver, and its activity was analyzed by γ-32P incorporation technique to detect the phosphorylation of myosin light chain.RESULTS: MLCK was expressed in rabbit liver, and the activity of the enzyme was similar to rabbit smooth muscle MLCK, and calmodulin-dependent. When the concentration was 0.65 mg-L-1, the activity was at the highest level.CONCLUSION: MLCK expressed in rabbit liver may catalyze the phosphorylation of myosin light chain, which may play important roles in the regulation of hepatic cell functions.
文摘Summary: To study whether there was an anti-cardiac myosin antibody (AMA) in serum of pa- tients with myocardial infarction (AMI), relationship between AMA and the prognosis in patients with AMI was investigated. In 67 patients with acute AMI, AMA was assayed by ELISA and left ventricular structure and cardiac function were examined by echocardiography at the end of the first week after infarction and during a 6-month follow-up. The patients with AMI were divided into AMA-positive group and AMA-negative group. The parameters of left ventricular end-dias- tolic function and prognosis were compared between the two groups. Results showed that the AMA was positive in 18 patients with AMI, with a positive rate of 26. 87 %, while it was negative in 20 health donors. The locations of myocardial infarction in the two groups were similar. There were significant differences in Killip class I (22. 22 % vs 55. 10 %, P<0. 05), decreasing of wall motion and ventricular aneurysm (92. 85 % vs 37. 5 %, P<0.01) between the positive group and the negative group. During a 6-month follow-up, the mortality was higher in AMA positive group than in AMA negative group (38. 89% vs 10. 20 %, P<0. 05). It is concluded that AMA can be detected in serum of patients with AMI and can serve as an important autoimmune marker. The autoimmune response might take place in AMI. AMA was associated with the left ventricular re- modeling and the prognosis of AMI.
基金supported by a grant from National Key Basic Research Program of China (No.2007CB512000,Sub-Project No.2007CB512005)
文摘Autoimmune is involved in the pathogenesis of ventricular remodeling in acute myocardial infarction (AMI).In the present study, we investigated the effect of anti-cardiac myosin heavy chain antibodies (AMHCA) from patients with AMI on rat cardiomyocyte apoptosis.Cardiomyocyte apoptosis was observed and measured by DNA end labeling and Annexin-Ⅴ/PI double-staining assay.The expression of apoptosis related p53 and Bcl-2 protein and the second messenger calcium were detected respectively by Western blotting, patch clamp and confocal calcium imaging.The results showed that AMHCA was able to induce cardiomyocyte apoptosis in a dose dependent manner.Apoptosis-accelerating nucleoprotein p53 was up-regulated, while apoptosis-inhibiting cytoplasmic protein Bcl-2 was down-regulated.In parallel, cytoplasmic calcium concentration was elevated.There was no effect on L-type calcium currents.It is concluded that AMHCA in patients with AMI as a novel triggering factor can induce cardiomyocyte apoptosis, which contributes to ventricular remodeling.
文摘AIM: To identify and characterize the function of non-mu-scle myosin Ⅱ (NMM Ⅱ) isoforms in primary rat hepatic stellate cells (HSCs).METHODS: Primary HSCs were isolated from male Spra-gue-Dawley rats by pronase/collagenase digestion. Total RNA and protein were harvested from quiescent and culture-activated HSCs. NMM Ⅱ isoform (Ⅱ-A, Ⅱ-B and Ⅱ-C) gene and protein expression were measured by RealTime polymerase chain reaction and Western blot analyses respectively. NMM Ⅱ protein localization was visualized in vitro using immunocytochemical analysis. For in vivo assessment, liver tissue was harvested from bile duct-ligated (BDL) rats and NMM Ⅱisoform expression determined by immunohistochemistry. Using a selective myosin Ⅱ inhibitor and siRNA-mediated knockdown of each isoform, NMM Ⅱ functionality inprimary rat HSCs was determined by contraction and migration assays.RESULTS: NMM Ⅱ-A and Ⅱ-B mRNA expression was increased in culture-activated HSCs (Day 14) with sig-niflicant increases seen in all pairwise comparisons (Ⅱ-A: 12.67 ± 0.99 (quiescent) vs 17.36 ± 0.78 (Day 14), P < 0.05; Ⅱ-B: 4.94 ± 0.62 (quiescent) vs 13.90 ±0.85 (Day 14), P < 0.001). Protein expression exhibited similar expression patterns (Ⅱ-A: 1.87 ± 2.50 (quiescent) vs 58.64 ± 8.76 (Day 14), P < 0.05; Ⅱ-B: 1.17 ± 1.93 (quiescent) vs 103.71 ± 21.73 (Day 14), P < 0.05). No signif icant differences were observed in NMM Ⅱ-C mRNA and protein expression between quiescent and activated HSCs. In culture-activated HSCs, NMM Ⅱ-A and Ⅱ-B merged with F-actin at the cellular periphery and throughout cytoplasm respectively. In vitro stud-ies showed increased expression of NMM Ⅱ-B in HSCs activated by BDL compared to sham-operated animals. There were no apparent increases of NMM Ⅱ-A and Ⅱ-C protein expression in HSCs during hepatic BDL injury. To determine the contribution of NMM Ⅱ-A and Ⅱ-B to migration and contraction, NMM Ⅱ-A and Ⅱ-B expres-sion were downregulated with siRNA. NMM Ⅱ-A and/or Ⅱ-B siRNA inhibited HSC migration by approximately 25% compared to scramble siRNA-treated cells. Conversely, siRNA-mediated NMM Ⅱ-A and Ⅱ-B inhibition had no signif icant effect on HSC contraction; however, contraction was inhibited with the myosin Ⅱ inhibitor, blebbistatin (38.7% ± 1.9%).CONCLUSION: Increased expression of NMM Ⅱ-A and Ⅱ-B regulates HSC migration, while other myosin Ⅱclasses likely modulate contraction, contributing to development and severity of liver f ibrosis.
基金supported by the National Natural Science Foundation of China (30070365, 30470861, 30971706)the Natural Science Foundation of Hebei Province, China (C2008000321)the Specialized Research Fund for the Doctoral Program of Higher Education, China (20060086003)
文摘Actin and myosin were found to be associated with the cytoplasmic sleeve of plasmodesmata. As cytoskeletal proteins, actin and myosin are believed to regulate the conductivity of plasmodesmata (PDs) in higher plants. Using immunocytochemical methods, we found the two proteins to be co-localized - and closely linked to each other - in plasmodesmata and ectodesmata-like structure in ageing parenchymatous cells of Allium sativum L. We suggest that intercellular communication is affected by the interaction between actin and myosin.
基金supported by 863 Program Key Project (2007AA042100)the Natural Science Foundation of Shaanxi Province (No.2007C216)
文摘Objective To study the effect of 4-6 weeks’ treadmill training of male SD rats on the contractile function of their gastrocnemius myosin heavy chain (MHC). Methods Forty male SD rats were randomly divided into control group and training group. The treadmill training of the training group rats was incessantly performed for 4-6 weeks at an intensity of about 75% VO2max (18.5-24 m/min,gradient of 0°,each training session lasting 50 minutes,twice a day). The content of gastrocnemius MHC mRNA was tested by reverse transcription polymerase chain reaction (RT-PCR),and the changes of muscle fibre and its cross-section area (CSA) were measured using immunohistochemistry. Electric stimulation tests were used to determine the maximal tension of isometric contraction of the post-training gastrocnemius. Results ① After continuous treadmill training for 4-6 weeks,we found that the content of the total MHC,MHC Ⅰ,MHC Ⅱx,MHC Ⅱa mRNAs was 105%,105%,109% and 108% of that in the resting control group,respectively,and the MHC Ⅱb mRNA content did not change significantly. The percentage of MHC Ⅰ mRNA in the total MHC mRNA increased while that of MHC Ⅱ mRNA decreased after aerobic training. ② The slow type of fibre type Ⅰ was the main part of the MHC after training and the CSA of the muscle fibres increased simultaneously. ③ The maximal tension of isometric contraction by pulse stimulation of square wave in the training group increased significantly compared with that in the control group (P<0.01). Conclusion The findings indicate that aerobic exercise may promote an increase in the contractile function of MHC.
文摘Experimental mice were immunized with cardiac myosin and complete Freunds adjuvant (CFA) on days 0, 7 and 30 and control mice were immunized with CFA. Sera and myocardium samples were harvested on days 15, 21 and 120 after the first immunization. Pathological findings demonstrated that there were necrosis and inflammatory infiltration in acute stage and fibrosis mainly in chronic stage of experimental group. Anti myosin antibodies were also found in sera of experimental mice, but not in control group. Our study showed that cardiac myosin served as an autoantigen to provoke autoimmunity and lead to the transformation of VMC into DCM.
文摘Myostatin is a major factor involved in the regulation of skeletal muscle protein mass. High myostatin levels have been associated with an increase in myotube shrinkage. Enhanced myostatin expression is caused by pro-catabolic reactions involving compounds such as tumor necrosis factor (TNF)-α. The present study investigated the effects of agaro-oligosaccharides (AOSs) on hypercatabolism of myotubes exposed to TNF-α. C2C12 myotubes exposed to TNF-α in the presence or absence of AOSs. Myotube exposure to TNF-α resulted in a reduction in the amount of myosin heavy chain (MyHC) protein and a decrease in myotube diameter, which was associated with increased myostatin mRNA expression. AOSs prevented TNF-α-induced MyHC protein loss and restored normal myostatin mRNA levels, with agarobiose and agarotetraose effectively suppressing the hyperexpression of the mRNA. In addition, expression levels of the known myostatin inhibitors, latent transforming growth factor beta binding protein 3 (Ltbp3) and growth and differentiation factor-associated serum protein 1 (Gasp1) mRNAs, decreased more in TNF-α-induced myotubes than in the TNF-α-free control, possibly resulting in myostatin upregulation. However, AOSs restored nearly normal expression levels of Ltbp3 and Gasp1 mRNA, potentially suppressing myostatin expression. These findings suggest that AOSs could prevent myotube shrinkage induced by TNF-α.
文摘Protein phosphorylation plays an important role in physiological processes, such as muscle contraction. Phospho-specific antibodies have become powerful tools to study these processes. Cardiac myosin binding protein-C (cMyBP-C) is one of the proteins that make up the contractile apparatus of cardiomyocytes. Phosphorylation of cMyBP-C is essential for normal cardiac function, since dephosphorylation of this protein leads to its degradation and has been associated with cardiomyopathy. One of the upstream kinases, which phosphorylate cMyBP-C, is protein kinase D (PKD). While studying the role of PKD in cMyBP-C phosphorylation, we tried to analyze phosphorylation of PKD with a phospho-specific PKD-Ser744/748 antibody. Contrary to the expected 115 kDa, a signal was found for a 150-kDa protein. By MALDI-TOF mass spectrometry, we identified this protein to be cMyBP-C. These data were confirmed by immunostaining using the p-PKD-Ser744/748 antibody, which displayed a striated pattern similar to the one observed for a regular cMyBP-C antibody. To our knowledge there are no antibodies commercially available for phosphorylated cMyBP-C. Thus, the p-PKD-Ser744/748 antibody can accelerate research into the role of cMyBP-C phosphorylation in cardiomyocytes.