The PROS-35 gene encodes the 35 kd protein subunit of Drosophila melanogaster proteasome

The proteasome is a multicatalytic proteinase complex composed of nonidentical protein subunits. We have isolated a cDNA clone encoding the 35 kd proteasome subunit of Drosophila melanogaster and propose the designation PROS-35 for the corresponding gene. The deduced amino acid sequence reveals a region of striking homology to a tyrosine phosphorylation site of viral and cellular proteins suggesting a potential regulatory function for the 35 kd subunit within the proteinase complex. Immunocytochemical experiments reveal a tissue-dependent differential distribution of the proteasome between the nucleus and cytoplasm. In addition developmental analysis shows that the proteasome is highly expressed in the CNS of stage-16 embryos and in cardia, ventriculus and ovaries of adult flies. These data suggest a tissue- and development-dependent distribution of the proteasome in D. melanogaster.