The muscle protein myosin binding protein C (MyBPC) is a large multi-domain protein whose role in the sarcomere is complex and not yet fully understood. Mutations in MyBPC are strongly associated with the heart diseas...The muscle protein myosin binding protein C (MyBPC) is a large multi-domain protein whose role in the sarcomere is complex and not yet fully understood. Mutations in MyBPC are strongly associated with the heart disease familial hypertrophic cardiomyopathy (FHC) and these experiments of nature have provided some insight into the intricate workings of this protein in the heart. While some regions of the MyBPC molecule have been assigned a function in the regulation of muscle contraction, the interaction of other regions with various parts of the myosin molecule and the sarcomeric proteins, actin and titin, remain obscure. In additic n, several intra-domain interactions between adjacent MyBPC molecules have been identified. Although the basic structure of the molecule (a series of immunoglobulin and fibronectin domains) has been elucidated, the assembly of MyBPC in the sarcomere is a topic for debate. By analysing the MyBPC sequence with respect to FHC-causing mutations it is possible to identify individual residues or regions of each domain that may be important either for binding or regulation. This review looks at the current literature, in concert with alignments and the structural models of MyBPC, in an attempt to understand how FHC mutations may lead to the disease state.展开更多
Class A scavenger receptor(SR-A) plays an important role in foam cell formation.However, the mechanism underlying the internalization of the receptor-ligand complexes remains unclear.The aim of the present study was t...Class A scavenger receptor(SR-A) plays an important role in foam cell formation.However, the mechanism underlying the internalization of the receptor-ligand complexes remains unclear.The aim of the present study was to investigate the molecular mechanism to regulate SR-A-mediated intracellular lipid accumulation in macrophages A pull-clown assay was performed and glucoseregulated protein 78(GRP78) was identified to bind with the cytoplasmic domain of SR-A(CSR-A).Immunoprecipitation and artificially expressed protein binding assay demonstrated the direct specific binding of GRP78 with SR-A in cells.Indirect immunofluorescence assay and western blot analysis showed their co-localization in membrane and cytoplasm.Over-expression of GRP78 specifically inhibited SR-A-mediated uptake of fluorescent acetylated low-density lipoprotein, a specific ligand for SR-A, without altering cellular SR-A expression and binding ability, and significantly inhibited cholesterol ester accumulation in cells, which can be partly attributed to the suppression of c-Jun-NH2-terminal kinase signaling pathway.These results suggest that GRP78 may act as an inhibitor of SR-A-mediated internalization of modified low-density lipoprotein into macrophages(C) 2009 Elsevier Inc.All rights reserved.展开更多
文摘The muscle protein myosin binding protein C (MyBPC) is a large multi-domain protein whose role in the sarcomere is complex and not yet fully understood. Mutations in MyBPC are strongly associated with the heart disease familial hypertrophic cardiomyopathy (FHC) and these experiments of nature have provided some insight into the intricate workings of this protein in the heart. While some regions of the MyBPC molecule have been assigned a function in the regulation of muscle contraction, the interaction of other regions with various parts of the myosin molecule and the sarcomeric proteins, actin and titin, remain obscure. In additic n, several intra-domain interactions between adjacent MyBPC molecules have been identified. Although the basic structure of the molecule (a series of immunoglobulin and fibronectin domains) has been elucidated, the assembly of MyBPC in the sarcomere is a topic for debate. By analysing the MyBPC sequence with respect to FHC-causing mutations it is possible to identify individual residues or regions of each domain that may be important either for binding or regulation. This review looks at the current literature, in concert with alignments and the structural models of MyBPC, in an attempt to understand how FHC mutations may lead to the disease state.
文摘Class A scavenger receptor(SR-A) plays an important role in foam cell formation.However, the mechanism underlying the internalization of the receptor-ligand complexes remains unclear.The aim of the present study was to investigate the molecular mechanism to regulate SR-A-mediated intracellular lipid accumulation in macrophages A pull-clown assay was performed and glucoseregulated protein 78(GRP78) was identified to bind with the cytoplasmic domain of SR-A(CSR-A).Immunoprecipitation and artificially expressed protein binding assay demonstrated the direct specific binding of GRP78 with SR-A in cells.Indirect immunofluorescence assay and western blot analysis showed their co-localization in membrane and cytoplasm.Over-expression of GRP78 specifically inhibited SR-A-mediated uptake of fluorescent acetylated low-density lipoprotein, a specific ligand for SR-A, without altering cellular SR-A expression and binding ability, and significantly inhibited cholesterol ester accumulation in cells, which can be partly attributed to the suppression of c-Jun-NH2-terminal kinase signaling pathway.These results suggest that GRP78 may act as an inhibitor of SR-A-mediated internalization of modified low-density lipoprotein into macrophages(C) 2009 Elsevier Inc.All rights reserved.
