AIMTo establish a system of mitochondrial translation in vitro of rat brain and identify it's production of protein by molecular weight.

METHODSMitochondria isolated from hemisphere of rat brain by differential centrifugations. The optimization of mitochondrial translation in vitro by 3H-Lencine incorporation was explored. 35S-methionine labeled products of mitochondrial protein synthesis were identified by SDS-PAGE and fluorography.

RESULTSIsolated mitochondria had a highly activity oxidative phosphorylation and respiratory control ratio (RCR) was between 3.5 and 5.5. The activity of 3H-Lencine incorporation in isolated mitochondria in vitro increased with time of incubation in 60 min and maintained a steady level. The maximal activity of 3H-Lencine incorporation per milligram mitochondria protein occured at 1 mg mitochondria/ml of incubation mix.The major auto radiographic bands could be observed at 86, 68, 56, 43, 33, 29, 25 and 18(kD) molecular weight separated on SDS-PAGE.

CONCLUSIONThe translation system of rat brain mitochondria in vitro is faithful and high activity, can be used to study mtDNA expression and regulation in mammalian brain at the level of translation.