ISSN:
1573-4978
Keywords:
arthropod
;
crustacean
;
Drosophila
;
insect
;
lobster
;
multicatalyic proteinase
;
proteasome
;
ubiquitin
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Recent work on structural/functional relationships in arthropod proteasomes is reviewed. Taking advantage of our ability to induce a stable, proteolytically-active conformation of the lobster proteasome, the structures of basal and heat-activated complexes were probed with exogenous proteases. Increased sensitivity to chymotrypsin and trypsin showed that heat activation induced a more ‘open’ conformation, allowing entry of large substrates into the catalytic chamber. In Drosophila, the effects of two developmental mutant alleles (DTS-7 and DTS-5) encoding proteasome subunits (Z and C5, respectively) on the subunit composition and catalytic activities of the enzyme were examined. Both qualitative and quantitative differences in compositions between wild-type (+/+) and heterozygotes (+/DTS) indicated that incorporation of mutant subunits alters post-translational modifications of the complex. Catalytic activities, however, were similar, which suggests that the developmental defect involves other proteasome properties, such as intracellular localization and/or interactions with endogenous regulators. A hypothetical model in which DTS subunits act as poison subunits is presented.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1006976524916
