Nonuniform distribution of myosin light chains within the thick filaments of lobster slow muscle: Immunocytochemical study.
The in situ distribution of the alpha and beta myosin light chains was investigated at the subsarcomeric and subfilament levels in individual fibers of the superficial flexor muscle (SFM) of the lobster, Homarus americanus. Polyclonal antibodies were produced against the two classes of myosin light chains and used for subsequent immunolocalization on thin sections of sarcomeres and on isolated filaments from both the medial and lateral fiber bundles of the SFM. The beta myosin light chains were uniformly distributed within the crossbridge region of sarcomeres of both medial and lateral bundles. The alpha myosin light chains were uniformly distributed within the crossbridge region of sarcomeres from the medial bundle, but were nonuniformly distributed over the crossbridge region of lateral bundle sarcomeres. In the latter, the number of alpha myosin light chains was highest toward the center of the thick filaments, diminishing towards the ends. Similar distributions of alpha light chains were found in isolated myosin filaments. These data demonstrate that heterogeneity in protein composition extends to the level of the myosin filament and suggest that the myosin filament substructure in lobster may be different than that found in vertebrate skeletal muscle.
Brown
L D
LD
Department of Physiology and Neurobiology, The University of Connecticut, Storrs, Connecticut 06268, USA. lbrow001@umaryland.edu
Cantino
M E
ME
D000818:Animals; D000906:Antibodies; D015151:Immunoblotting; D007150:Immunohistochemistry; D018657:Muscle Fibers, Slow-Twitch / Q000737:chemistry* / Q000276:immunology / Q000648:ultrastructure; D018994:Myosin Light Chains / Q000032:analysis* / Q000276:immunology; D008121:Nephropidae / Q000502:physiology*; D012518:Sarcomeres
D000906:Antibodies; D018994:Myosin Light Chains