The beta-isoform of the BRCA2 and CDKN1A(p21)-interacting protein (BCCIP) stabilizes nuclear RPL23/uL14

BRCA2 and CDKN1A(p21,CIP1)-interacting protein (BCCIP) is an evolutionary conserved protein implicated in maintenance of genome stability and cell cycle progression. Two isoforms of BCCIP with distinct C-terminal domains exist in humans. We show that mammalian BCCIP beta, but not BCCIP alpha, forms a ternary complex with the ribosomal protein RPL23/uL14 and the pre-60S transacting factor eIF6. Complex formation is dependent on an intact C-terminal domain of BCCIP beta. Depletion of BCCIP beta reduces the pool of free RPL23, and decreases eIF6 levels in nucleoli. Overexpression of BCCIP beta leads to nucleoplasmic accumulation of extra-ribosomal RPL23 and stabilizes overexpressed RPL23, suggesting that BCCIP beta functions as nuclear chaperone for RPL23. (C) 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.