IMMUNOHISTOCHEMICAL LOCALIZATION OF CONTRACTILE PROTEINS IN LIMULUS STRIATED MUSCLE |
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| Authors: | Rhea J C Levine Maynard M Dewey and George W de Villafranca |
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| Institution: | From the Department of Anatomy, The Medical College of Pennsylvania, Philadelphia, Pennsylvania 19129, the Department of Anatomical Sciences, School of Basic Sciences, Health Science Center, State University of New York at Stony Brook, Stony Brook, Long Island, New York 11790, and the Department of Biological Sciences, Smith College, Northampton, Massachusetts 01060 |
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| Abstract: | Limulus paramyosin and myosin were localized in the A bands of glycerinated Limulus striated muscle by the indirect horseradish peroxidase-labeled antibody and direct and indirect fluorescent antibody techniques. Localization of each protein in the A band varied with sarcomere length. Antiparamyosin was bound at the lateral margins of the A bands in long (~ 10.0 µ) and intermediate (~ 7.0 µ) length sarcomeres, and also in a thin line in the central A bands of sarcomeres, 7.0–~6.0 µ. Antiparamyosin stained the entire A bands of short sarcomeres (<6.0). Conversely, antimyosin stained the entire A bands of long sarcomeres, showed decreased intensity of central A band staining except for a thin medial line in intermediate length sarcomeres, and was bound only in the lateral A bands of short sarcomeres. These results are consistent with a model in which paramyosin comprises the core of the thick filament and myosin forms a cortex. Differential staining observed using antiparamyosin and antimyosin at various sarcomere lengths and changes in A band lengths reflect the extent of thick-thin filament interaction and conformational change in the thick filament during sarcomeric shortening. |
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