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

ABSTRACT

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 BCCIPß, but not BCCIPα, forms a ternary complex with the ribosomal protein RPL23/uL14 and the pre-60S trans-acting factor eIF6. Complex formation is dependent on an intact C-terminal domain of BCCIPß. Depletion of BCCIPß reduces the pool of free RPL23, and decreases eIF6 levels in nucleoli. Overexpression of BCCIPß leads to nucleoplasmic accumulation of extra-ribosomal RPL23 and stabilizes overexpressed RPL23, suggesting that BCCIPß functions as nuclear chaperone for RPL23.