Analysis of ubiquitin-dependent increase in monoamine oxidase sensitivity to proteolysis and specific inhibition

   
Buneeva O.A.1 , Medvedeva M.V.2, Medvedev A.E.1

1. Institute of Biomedical Chemistry, Russian Academy of Medical Sciences
2. School of Biology, Moscow State University
Section: Short Communication
UDK: 557.15.02;577.15.06      PubMed Id: 19205432
Year: 2008  Volume: 54  Issue: 6  Pages: 720-726
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.
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Buneeva O.A., Medvedeva M.V., Medvedev A.E. (2008) Biomeditsinskaya khimiya, 54(6), 720-726.
This paper is also available as the English translation:10.1134/S1990750809020048
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