Target size analysis by radiation inactivation of carnitine palmitoyltransferase activity and malonyl-CoA binding in outer membranes from rat liver mitochondria.
The functional molecular sizes of the protein(s) mediating the carnitine palmitoyltransferase I (CPT I) activity and the [14C]malonyl-CoA binding in purified outer-membrane preparations from rat liver mitochondria were determined by radiation-inactivation analysis. In all preparations tested the dose-dependent decay in [14C]malonyl-CoA binding was less steep than that for CPT I activity, suggesting that the protein involved in malonyl-CoA binding may be smaller than that catalysing the CPT I activity. The respective sizes computed from simultaneous analysis for molecular-size standards exposed under identical conditions were 60,000 and 83,000 DA for malonyl-CoA binding and CPT I activity respectively. In irradiated membranes the sensitivity of CPT activity to malonyl-CoA inhibition was increased, as judged by malonyl-CoA inhibition curves for the activity in control and in irradiated membranes that had received 20 Mrad radiation and in which CPT activity had decayed by 60%. Possible correlations between these data and other recent observations on the CPT system are discussed.
Zammit
V A
VA
Hannah Research Institute, Scotland, U.K.
Corstorphine
C G
CG
Kolodziej
M P
MP
D000214:Acyl Coenzyme A / Q000528:radiation effects*; D000217:Acyltransferases / Q000528:radiation effects*; D000818:Animals; D002334:Carnitine O-Palmitoyltransferase / Q000037:antagonists & inhibitors / Q000528:radiation effects*; D002384:Catalysis; D004307:Dose-Response Relationship, Radiation; D007425:Intracellular Membranes / Q000201:enzymology / Q000378:metabolism; D008297:Male; D008316:Malonyl Coenzyme A / Q000378:metabolism / Q000528:radiation effects*; D008930:Mitochondria, Liver / Q000201:enzymology* / Q000378:metabolism; D008970:Molecular Weight; D051381:Rats; D011919:Rats, Inbred Strains
D000214:Acyl Coenzyme A; D008316:Malonyl Coenzyme A; D000217:Acyltransferases; D002334:Carnitine O-Palmitoyltransferase