Cardiac and skeletal myosin assembled in the muscle lattice power contraction by transducing ATP free energy into the mechanical work of moving actin. Myosin catalytic/lever-arm domains comprise the transduction/mechanical coupling machinery that move actin by lever-arm rotation. In vivo, myosin is crowded and constrained by the fiber lattice as side chains are mutated and otherwise modified un...

Myosin isoenzyme profiles of rat and chicken embryonic cardiac myocytes were studied during differentiation and growth in vitro by native-gel electrophoresis and assay of Ca2+-activated ATPase. The electrophoretic pattern of myosin extracted from 18-day-embryonic-rat myocytes after 7 days in culture exhibits three isoenzyme bands, V1, V2 and V3, of which the slow-migrating V3 is predominant. Th...

Sarcomeres, bundled into thick and thin filaments, are the units of contraction in the striated muscle. The thick filaments comprise several hundred hexameric myosin molecules, composed of 2 myosin heavy chain (MyHC) proteins, the molecular motor of contraction, and 2 regulatory and 2 essential light chains. The globular head of MyHC contains the binding domains for cardiac -actin and adenosine...

OBJECTIVE To study the molecular markers for the genes of the heavy chain of cardiac beta-myosin and the myosin binding protein C in relatives of carriers of hypertrophic cardiomyopathy. METHODS Twelve families who had anamnesis, physical exam, electrocardiogram, echocardiogram and blood collection for the genetic study through the chain reaction of polymerase. RESULTS From the 227 relative...

The expression of different isoforms of the contractile protein myosin plays a major role in determining contractile characteristics in both cardiac and skeletal muscle in the adult. There is little evidence pertaining to putative changes in myosin phenotype during cardiac embryogenesis or if such changes could play a role in modulating the contractile characteristics of the developing heart. W...

RATIONALE Molecular mimicry theory (MMT) suggests that epitope mimicry between pathogens and human proteins can activate autoimmune disease. Group A streptococci (GAS) mimics human cardiac myosin in rheumatic heart disease (RHD) and coxsackie viruses (CX) mimic actin in autoimmune myocarditis (AM). But myosin and actin are immunologically inaccessible and unlikely initial targets. Extracellular...

BACKGROUND Anesthetic-induced malignant hyperthermia (MH) in humans and pigs is associated with dramatic alterations in cardiac function. However, it remains controversial as to whether MH-associated cardiac symptoms represent a primary difference of myocardium or a secondary alteration consequent to increases in the hyperthermic stress. Here the authors describe changes in myosin isoform expre...

Cardiac β-myosin variants cause hypertrophic (HCM) or dilated (DCM) cardiomyopathy by disrupting sarcomere contraction and relaxation. The locations of variants on isolated myosin head structures predict contractility effects but not the prominent relaxation and energetic deficits that characterize HCM. During relaxation, pairs of myosins form interacting-heads motif (IHM) structures that with ...

Myosin is a chemomechanical motor that converts chemical energy into the mechanical work of muscle contraction. More than 40 missense mutations in the cardiac myosin heavy chain (MHC) gene and several mutations in the two myosin light chains cause a dominantly inherited heart disease called familial hypertrophic cardiomyopathy. Very little is known about the biochemical defects in these alleles...

Expression of the two isoforms of cardiac myosin heavy chain (MHC), MHC alpha and MHC beta, in mammals is regulated postnatally by a variety of stimuli, including serum hormone levels. Less is known about the factors that regulate myosin gene expression in rapidly growing cardiac muscle in embryos. Using isoform-specific 35S-labeled cRNA probes corresponding to the two MHC genes and the two myo...