Interaction between alphaB-crystallin and the human 20S proteasomal subunit C8/alpha7.
alphaB-Crystallin, a member of the small heat shock protein (sHsp) family, can bind unfolding proteins, but is unable to refold them. To fulfil its protective function in vivo it is therefore likely to interact with other cellular proteins. Here we report that alphaB-crystallin binds very specifically both in vitro and in vivo to C8/alpha7, one of the 14 subunits of the 20S proteasome. The C8/alpha7 protein forms heterogeneous complexes with alphaB-crystallin of about 540 kDa. However, no strong interaction between alphaB-crystallin and 20S proteasomes was observed. Since both proteins are localized in the cytoplasm, the interaction between alphaB-crystallin and C8/alpha7 subunit might affect the assembly of the proteasome complex or facilitate the degradation of unfolded proteins bound to alphaB-crystallin.
Boelens
W C
WC
Department of Biochemistry, University of Nijmegen, PO Box 9101, 6500 HB, Nijmegen, The Netherlands. w.boelens@bioch.kun.nl
Croes
Y
Y
de Jong
W W
WW
D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003459:Crystallins / Q000378:metabolism*; D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D009097:Multienzyme Complexes / Q000737:chemistry / Q000378:metabolism*; D011233:Precipitin Tests; D046988:Proteasome Endopeptidase Complex; D011485:Protein Binding; D020798:Two-Hybrid System Techniques
D003459:Crystallins; D009097:Multienzyme Complexes; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex