Abstract: Incubation of rat brain mitochondria with ubiquitin and ATP followed by subsequent mitochondria sedimentation was accompanied by reduction of ubiquitin content in the supernatant. This decrease was more pronounced in the presence of ATP-regenerating system in the incubation medium (creatine phosphate/creatine phosphokinase). This ubiquitin incorporation into brain mitochondria observed only in the presence of ATP in the incubation medium increased sensitivity of monoamine oxidases (MAO) A and B to proteolytic inactivation by trypsin and papain, respectively. (Ubiquitin did not influence sensitivity of MAO B to trypsin and MAO A to papain). The data obtained suggest that ubiquitin incorporation into rat brain mitochondria increases susceptibility of MAOs to certain exogenous proteases, however, it remains unclear whether these changes stem from direct MAO-ubiquitin conjugation or reflect alterations in the membrane environment of these enzymes.
Reference: Buneeva O.A., Medvedeva M.V., Medvedev A.E., Ubiquitin causes selective increase in the sensitivity of rat brain mitochondrial monoamine oxidases to various proteases, Biomeditsinskaya khimiya, 2007, vol: