Expression of hybrid isomyosins in human skeletal muscle.
Myosin of human skeletal muscles was analyzed by means of several electrophoretic techniques. Myosin heavy chain (HC)-IIa-and HC-IIb-based isomyosins were identified by pyrophosphate-polyacrylamide gel electrophoresis (PP-PAGE). The electrophoretic mobilities of these fast-twitch muscle isomyosins differed in the order HC-IIa triplets < HC-IIb triplets. To determine the subunit composition of myosin molecules that function in intact muscle, two-dimensional electrophoresis in which the first and second dimensions were PP-PAGE and sodium dodecyl sulfate-PAGE, respectively, was also performed. Slow-twitch muscle isomyosin contained, in addition to slow-twitch light chain (LC) and HC-I isoforms, appreciable amounts of LC-2f, HC-IIa, and HC-IIb isoforms, and fast-twitch muscle isomyosin consisted of LC-2s and HC-I isoforms as well as fast-twitch LC and HC isoforms. Without consideration of HC- and slow-twitch alkali LC heterodimers, at least 31 possible isomyosins are derived from these findings on the subunit composition of isomyosins in human skeletal muscle.
Wada
M
M
Faculty of Integrated Arts and Sciences, Hiroshima University, Japan.
Okumoto
T
T
Toro
K
K
Masuda
K
K
Fukubayashi
T
T
Kikuchi
K
K
Niihata
S
S
Katsuta
S
S
D011756:Diphosphates; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007526:Isoelectric Point; D007527:Isoenzymes / Q000737:chemistry*; D008970:Molecular Weight; D018482:Muscle, Skeletal / Q000201:enzymology*; D018995:Myosin Heavy Chains / Q000737:chemistry*; D018994:Myosin Light Chains / Q000737:chemistry*
D011756:Diphosphates; D007527:Isoenzymes; D018994:Myosin Light Chains; D018995:Myosin Heavy Chains