Effects of denervation on the composition and synthesis of sarcolemmal proteins |
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Authors: | Ira Wallis Edward Koenig |
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Institution: | Division of Neurobiology, Department of Physiology, State University of New York at Buffalo, 319 Cary Hall, Buffalo, NY 14214 U.S.A. |
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Abstract: | In vitro synthesis of proteins and changes in polypeptide composition of sarcolemma were studied in innervated and denervated extensor digitorum longus muscle of the rat. A technique of evacuating myoplasm from muscle slices was used as a preliminary step in the preparation of three membrane fractions, M, H and S, containing sarcolemma. On the basis of findings from the previous study and the present investigation, it was concluded that the M fraction was most enriched with extrajunctional sarcolemma.In vitro incorporation of 3H]leucine into membrane proteins of the M fraction showed an apparent linear increase in the rate of protein synthesis from 1–10 days after denervation. The relative increase at 10 days was 137% greater than that of innervated controls. Fractions H and S showed a smaller relative increase.Polypeptide composition of M, H and S fractions based on SDS gel electrophoresis of innervated and denervated muscle, showed qualitative and quantitative changes. The most striking difference was a nominal 29 000 component in M that constituted a disproportionately large peak. Following 10 days of denervation the M fraction underwent significant compositional changes in its electrophoretic profile, the most dramatic of which was a large reduction in the proportion of the 29 000 component. The denervation-induced compositional change is discussed in light of known alterations in the chloride conductance of the muscle plasmalemma. |
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Keywords: | Sarcolemma protein Protein synthesis Denervation (Rat skeletal muscle) |
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