title: Myomesin and M-protein: expression of two M-band proteins in pectoral muscle and heart during development.
abstract: The expression of the myofibrillar M-band proteins myomesin and M-protein was studied in chicken pectoral muscle and heart during differentiation using monoclonal antibodies in a double-antibody sandwich enzyme-linked immunosorbent assay, immunoblotting, and immunocytochemistry. In presumptive pectoral muscle, myomesin accumulated first, increasing from 2% of the adult concentration at day 7 to 70% by day 16 in ovo. M-protein accumulation lagged 6-7 d behind that of myomesin attaining only 40% of the adult concentration in ovo. The molecular masses of myomesin (185 kD) and M-protein (165 kD) remained constant during embryogenesis. In cultured myogenic cells the accumulation and M-band localization of myomesin preceded that of M-protein by 1.5 d. Chicken heart was shown, in addition to M-protein, to contain unique isoforms of myomesin. In hearts of 6 d embryos, a 195-kD myomesin isoform was the major species; throughout development, however, a transition to a mixture of 195 and 190 kD was observed, the latter being the major species in the adult tissue. During heart differentiation the initial accumulation of myomesin again preceded that of M-protein, albeit on an earlier time scale than in pectoral muscle with M-protein reaching adult proportions first.
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002478:Cells, Cultured; D002642:Chick Embryo; D002645:Chickens / Q000254:growth & development; D064211:Connectin; D005786:Gene Expression Regulation; D006321:Heart / Q000196:embryology; D009124:Muscle Proteins / Q000096:biosynthesis* / Q000502:physiology; D009206:Myocardium / Q000378:metabolism*; D009210:Myofibrils / Q000378:metabolism; D010369:Pectoralis Muscles / Q000196:embryology / Q000378:metabolism*
chemical_list: D064211:Connectin; D009124:Muscle Proteins