IDENTIFICATION OF AN ESSENTIAL GENE, L(3)73AI, WITH A DOMINANT TEMPERATURE-SENSITIVE LETHAL ALLELE, ENCODING A DROSOPHILA PROTEASOME SUBUNIT

Proteasomes are multicatalytic proteinase complexes that function as a major nonlysosomal proteolytic system in all eukaryotes. These partic les are made up of 13-15 nonidentical subunits, and they exhibit multi ple endopeptidase activities that promote the intracellular turnover o f abnormal polypeptides and short-lived regulatory proteins. Although the biochemical characterization of proteasomes has been quite extensi ve, and although a number of the genes encoding proteasome subunits ha ve been cloned from various organisms, there is still much to be learn ed about their function in vivo and what role(s) they might play durin g development. Here, we report the identification of the l(3)73Ai1 all ele of Drosophila melanogaster as a dominant temperature-sensitive let hal mutation in a gene encoding a component of the proteasome, thus op ening the way for future genetic and developmental studies on this imp ortant proteolytic system in a higher eukaryote.