Biogenesis of mitochondrial proteins. Identification of the mature and precursor forms of the subunit of delta-aminolevulinate synthase from embryonic chick liver.
The purpose of this study was to determine the molecular weights of the mature subunit of embryonic chick liver delta-aminolevulinate synthase and of its putative precursor fom. Although an active enzyme with a subunit molecular weight of 51,000 could be purified from the livers of porphyric embryos, it was determined by immunoreplicate electrophoresis analyses of sodium dodecyl sulfate-solubilized liver homogenates and mitochondria from porphyric embryos that the actual molecular weight of the enzyme's subunit was 65,000 +/- 2,000. These results suggested that the usual procedure for purifying delta-aminolevulinate synthase from chick embryo yielded a partially degraded enzyme. When the products of cell-free translations of mRNA extracted from livers of porphyric embryos were analyzed, they contained a polypeptide of 75,000 +/- 400 daltons which specifically cross-reacted with anti-delta-aminolevulinate synthase. It is concluded that subunit of embryonic chick liver delta-aminolevulinate synthase present in mitochondria has a molecular weight of 65,000 and appears to be synthesized as a precursor of 75,000 daltons.
D000624:5-Aminolevulinate Synthetase / Q000096:biosynthesis* / Q000235:genetics; D000818:Animals; D002642:Chick Embryo; D004790:Enzyme Induction; D004792:Enzyme Precursors / Q000096:biosynthesis*; D007700:Kinetics; D008099:Liver / Q000196:embryology / Q000201:enzymology*; D046911:Macromolecular Substances; D008970:Molecular Weight; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics
D004792:Enzyme Precursors; D046911:Macromolecular Substances; D012333:RNA, Messenger; D000624:5-Aminolevulinate Synthetase