Transitions in membrane composition during postnatal development of rabbit fast muscle.
Early postnatal changes (4-5 days to 15 days after birth) in the biochemical composition of microsomes were investigated in rabbit skeletal muscles destined to become fast-twitch muscles. During this period, a steady decrease in the microsomal content of cholesterol and of ouabain-sensitive Na + /K + -ATPase activity, as well as a decrease in protein electrophoretic components in the 80 000-70 000 molecular weight range, were observed. These changes are probably due to a diminishing yield of microsomal membranes derived from T-tubules, as the age of the animals increases, and are indicated from a knowledge of the mixed composition of muscle microsomes and previous biochemical data on isolated T-tubules. The content of cytochrome b5, which was found to be high in muscle microsomes of newborn animals, decreased strikingly as the amount of membrane-bound Ca2 + -ATPase protein increased, with a crossing-over point at about 7-10 days after birth. These changes, possibly corresponding to a transition from precursor sarcoplasmic reticulum (SR) to mature SR, were found to be temporally correlated with changes in [3H] alpha-tocopherol binding ability of the microsomes and in the mitochondrial content of glycerol phosphate dehydrogenase. At the same critical periods, coincident with the onset of motile activity, the immunological cross-reactivity of the Ca2 + -ATPase protein of microsomal vesicles, with antibody specific for the Ca2 + -ATPase of adult fast SR, was found to increase markedly, as tested by competitive enzyme-linked immunosorbent assay (ELISA). The immunological data are consistent with data in the literature demonstrating an increase in the concentration of Ca2 + -ATPase molecules in the SR membranes during ontogenic development. Both these data and catalytic data, however, suggest that the Ca2 + -ATPase protein is present in the same form in the SR of immature and of adult fast muscle and, in an antigenically different form, in slow muscle SR.
D000818:Animals; D000252:Calcium-Transporting ATPases / Q000032:analysis / Q000276:immunology; D002155:Calsequestrin / Q000032:analysis; D007425:Intracellular Membranes / Q000032:analysis; D008565:Membrane Proteins / Q000032:analysis; D008861:Microsomes / Q000032:analysis; D008931:Mitochondria, Muscle / Q000032:analysis / Q000201:enzymology; D024510:Muscle Development; D009124:Muscle Proteins / Q000032:analysis; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000032:analysis*; D000254:Sodium-Potassium-Exchanging ATPase / Q000032:analysis
D002155:Calsequestrin; D008565:Membrane Proteins; D009124:Muscle Proteins; D000252:Calcium-Transporting ATPases; D000254:Sodium-Potassium-Exchanging ATPase