PMID: 2496119Apr 25, 1989Paper

Identification and characterization of three different subpopulations of the Drosophila multicatalytic proteinase (proteasome)

The Journal of Biological Chemistry
P E Falkenburg, P M Kloetzel

Abstract

In Drosophila melanogaster the population of proteasome particles consists of three distinct subclasses. By fractionation of a 40,000 x g supernatant of Drosophila homogenate on a DEAE-Sephacel column, proteasome particles which elute at salt concentrations of 200, 300, and 500 mM KAc can be separated. The proteasomes of all three subfractions sediment at 19 S in sucrose gradients and are shown by two-dimensional gel electrophoretic analysis to possess the same protein content. They differ, however, with respect to their specific proteolytic activity against the substrates benzoyl-Val-Gly-Arg-4-methylcoumaryl-7-amide, succinyl-Leu-Leu-Val-Tyr-4-methylcoumaryl-7-amide, and succinyl-Ala-Ala-Phe-4-methylcoumaryl-7-amide and the degree to which their hydrolytic activity can be enhanced by the addition of 30-110 microM sodium dodecyl sulfate (SDS). Our data show that the 200 mM proteasome fraction exhibits the lowest basal specific proteolytic activity but can be stimulated most by SDS. The 300 and 500 mM proteasome subfractions, on the other hand possess considerably higher but similar basal specific proteolytic activity. Of these only the proteolytic activity of the 300 mM subfraction against the substrates benzoyl-Val-Gly-Arg-4-m...Continue Reading

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