The troponin I: inhibitory peptide uncouples force generation and the cooperativity of contractile activation in mammalian skeletal muscle.

Hodges and his colleagues identified a 12 amino acid fragment of troponin I (TnI-ip) that inhibits Ca(2+)-activated force and reduces the effectiveness Ca(2+) as an activator. To understand the role of troponin C (TnC) in the extended cooperative interactions of thin filament activation, we compared the effect of TnI-ip with that of partial troponin TnC extraction. Both methods reduce maximal Ca(2+)-activated force and increase [Ca(2+)] required for activation.

Production of human skeletal alpha-actin proteins by the baculovirus expression system.

Mutations within the human skeletal muscle alpha-actin gene cause three different skeletal muscle diseases. Functional studies of the mutant proteins are necessary to better understand the pathogenesis of these diseases, however, no satisfactory system for the expression of mutant muscle actin proteins has been available. We investigated the baculovirus expression vector system (BEVS) for the abundant production of both normal and mutant skeletal muscle alpha-actin.

Differential effects of exercise training in men and women with chronic heart failure.

Background: Abnormalities of myosin heavy chain (MHC) isoforms, enzyme activity, and capillarity contribute to the exercise intolerance that is characteristic of patients with heart failure. To what extent these changes can be reversed with exercise training and whether differences exist in the responses of men and women remains uncertain. We described and compared the effects of exercise training on exercise capacity and skeletal muscle histochemistry in men and women with chronic heart failure.

The pathway of myofibrillogenesis determines the interrelationship between myosin and paramyosin synthesis in Caenorhabditis elegans.

Examination of null mutants in myosin B and paramyosin yields insights into the complex mechanisms that regulate expression of the three major components of Caenorhabditis elegans body-wall muscle thick filaments myosin A, myosin B and paramyosin. In the absence of myosin B, paramyosin accumulation is reduced, although neither its synthesis nor that of myosin A is affected. This implies that the interaction of myosin B with paramyosin inhibits paramyosin degradation.

The superfast extraocular myosin (MYH13) is localized to the innervation zone in both the global and orbital layers of rabbit extraocular muscle.

Extraocular muscles (EOMs) are the most molecularly heterogeneous and physiologically diverse mammalian striated muscles. They express the entire array of striated muscle myosins, including a specialized myosin heavy chain MYH13, which is restricted to extraocular and laryngeal muscles. EOMs also exhibit a breadth of contractile activity, from superfast saccades to slow tracking and convergence movements.

Phylogenetic implications of the superfast myosin in extraocular muscles.

Extraocular muscle exhibits higher-velocity and lower-tension contractions than other vertebrate striated muscles. These distinctive physiological properties are associated with the expression of a novel extraocular myosin heavy chain (MYH). Encoded by the MYH13 gene, the extraocular myosin heavy chain is a member of the fast/developmental MYH gene cluster on human chromosome 17 and the syntenic MYH cluster on mouse chromosome 11.