Vaults and telomerase share a common subunit, TEP1

Vaults are large cytoplasmic ribonucleoprotein complexes of undetermined fu nction. Mammalian vaults have two high molecular mass proteins of 193 and 2 40 kDa. We have identified a partial cDNA encoding the 240-kDa vault protei n and determined it is identical to the mammalian telomerase-associated com ponent, TEP1. TEP1 is the mammalian homolog of the Tetrahymena: p80 telomer ase protein and has been shown to interact specifically with mammalian telo merase RNA and the catalytic protein subunit hTERT. We show that while TEP1 is a component of the vault particle, vaults have no detectable telomerase activity. Using a yeast three-hybrid assay we demonstrate that several of the human vRNAs interact in a sequence-specific manner with TEP1. The prese nce of 16 WD40 repeats in the carboxyl terminus of the TEP1 protein is a co nvenient number for this protein to serve a structural or organizing role i n the vault, a particle with eight-fold symmetry. The sharing of the TEP1 p rotein between vaults and telomerase suggests that TEP1 may play a common r ole in some aspect of ribonucleoprotein structure, function, or assembly.