DISTRIBUTION OF TROPOMYOSIN ISOFORMS IN SPINY LOBSTER MUSCLES

Heterogeneity and tissue specificity of tropomyosin isoforms included in various muscles of the spiny lobster, Panulirus japonicus, were inv estigated using two-dimensional ureashift gel electrophoresis, two-dim ensional gel electrophoresis with first dimension isoelectric focusing and second dimension sodium dodecyl sulfate gels, and immunoblotting. Four kinds of tropomyosin isoforms were recognized as major component s in spiny lobster muscles, and distribution of these isoforms was con siderably tissue-specific. Three kinds of tropomyosin isoforms designa ted as TMa, TMb, and TMc in the present study were detected in abdomin al and cephalothoracic muscles. TMa was detected predominantly in fast muscles, TMb predominantly in slow muscles and it was the only isofor m in leg muscles, and TMc was found preferentially in the dorsal-side fast muscles. Six distribution patterns of tropomyosin isoforms, two f ast-type, two slow-type, thoracic-type and leg-type, were detected in the skeletal muscle tissues. A unique tropomyosin constituent designat ed as TMh was observed as the main component in the heart muscle. The antisera against TMa and TMb showed that these isoforms had the epitop es specific to the respective isoforms as well as those common to both isoforms. The antisera specific to TMa and TMb were prepared by absor ption of the antibodies common to both isoforms from the respective an tisera. From immunoblot analysis of TMc and TMh with the absorbed anti sera, it was shown that these isoforms had rather TMa-type antigenicit ies. (C) 1997 Wiley-Liss, Inc.