The synthesis of murine ferrochelatase in vitro and in vivo.
Ferrochelatase (protohaem ferro-lyase, EC 4.99.1.1), the terminal enzyme of the haem-biosynthetic pathway, is an integral membrane protein of the mitochondrial inner membrane. When murine erythroleukaemia cells are labelled in vivo with [35S]methionine, lysed, and the extract is immunoprecipitated with rabbit anti-(mouse ferrochelatase) antibody, a protein of Mr 40,000 is isolated. However, when isolated mouse RNA is translated in a cell-free reticulocyte extract, a protein of Mr 43,000 is isolated. Incubation of this Mr 43,000 protein with isolated mitochondria resulted in processing of the Mr 43,000 precursor to the Mr 40,000 mature-sized protein. Addition of carbonyl cyanide m-chlorophenylhydrazone and/or phenanthroline inhibits this processing. These data indicate that ferrochelatase, like most mitochondrial proteins, is synthesized in the cytoplasm as a larger precursor and is then translocated and processed to a mature-sized protein in an energy-required step.
Karr
S R
SR
Department of Microbiology, University of Georgia, Athens 30602.
Dailey
H A
HA
D000818:Animals; D002474:Cell-Free System; D004591:Electrophoresis, Polyacrylamide Gel; D004792:Enzyme Precursors / Q000378:metabolism; D005294:Ferrochelatase / Q000096:biosynthesis* / Q000235:genetics; D015151:Immunoblotting; D008190:Lyases / Q000096:biosynthesis*; D051379:Mice; D008930:Mitochondria, Liver / Q000201:enzymology; D010449:Peptide Mapping; D014176:Protein Biosynthesis; D014407:Tumor Cells, Cultured / Q000201:enzymology
D004792:Enzyme Precursors; D008190:Lyases; D005294:Ferrochelatase