[Analysis of ubiquitin-dependent regulation of the monoamine oxidase sensitivity to proteolysis and specific inhibition by pargyline].
Insertion of exogenous ubiquitin into rat brain mitochondria in the presence of ATP and the ATP-regenerating system (creatine phosphate/creatine phosphokinase) is accompanied by the increase in: i) sensitivity of mitochondrial monoamine oxidases A and B to proteolytic inactivation (by trypsin and papain, respectively); ii) inhibition by mechanism based inhibitor, pargyline; iii) in [3H]-pargyline insertion into mitochondria (+48 +/- 11%, p<0.01). There was almost fivefold increase in [3H]-pargyline incorporation into the fraction obtained by immunoprecipitation of mitochondrial proteins with anti-ubiquitin antiserum and protein A Sepharose. This suggests that MAO is a potential substrate for ubiquitination in vitro. However, the content of the tritium label in this fraction was less than 0.1% and not more than 0.25% of total radioactivity of [3H]pargyline bound to control and ATP-ubiquitin treated mitochondria, respectively. Insertion of ubiquitin into mitochondria did not influence molecular masses of [3H]-pargyline labeled proteins (MAO A and B). These results suggest that direct ubiquitination of MAO insignificantly contributes to marked changes in sensitivity of MAO A and MAO B to proteolysis and specific inhibition found under these experimental conditions. It is possible that more complex processes are involved into realization of these effects during ATP-dependent ubiquitin incorporation into mitochondria.
Buneeva
O A
OA
Medvedeva
M V
MV
Medvedev
A E
AE
D000818:Animals; D001921:Brain / Q000648:ultrastructure; D004591:Electrophoresis, Polyacrylamide Gel; D006868:Hydrolysis; D066298:In Vitro Techniques; D008928:Mitochondria / Q000378:metabolism*; D008995:Monoamine Oxidase / Q000378:metabolism*; D008996:Monoamine Oxidase Inhibitors / Q000494:pharmacology*; D010293:Pargyline / Q000494:pharmacology*; D051381:Rats; D025801:Ubiquitin / Q000378:metabolism*
D008996:Monoamine Oxidase Inhibitors; D025801:Ubiquitin; D010293:Pargyline; D008995:Monoamine Oxidase