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Identification of a protein component of a mammalian tRNASec complex implicated in the decoding of UGA as selenocysteine

Published online by Cambridge University Press:  28 August 2001

FENG DING
Affiliation:
Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
PAULA J. GRABOWSKI
Affiliation:
Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA Howard Hughes Medical Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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Abstract

This report describes a novel RNA-binding protein, SECp43, that associates specifically with mammalian selenocysteine tRNA (tRNASec). SECp43, identified from a degenerate PCR screen, is a highly conserved protein with two ribonucleoprotein-binding domains and a polar/acidic carboxy terminus. The protein and corresponding mRNA are generally expressed in rat tissues and mammalian cell lines. To gain insight into the biological role of SECp43, affinity-purified antibody was employed to identify its molecular partners. Surprisingly, the application of native HeLa cell extracts to a SECp43 antibody column results in the purification of a 90-nt RNA species identified by direct sequencing and Northern blot analysis as tRNASec. The purification of tRNASec by the antibody column is striking, based on the low abundance of this tRNA species. Using recombinant SECp43 as a probe for interacting protein partners, we also identify a 48-kDa interacting protein, which is a possible component of the mammalian selenocysteine insertion (SECIS) pathway. To our knowledge, SECp43 is the first cloned protein demonstrated to associate specifically with eukaryotic tRNASec.

Type
Research Article
Copyright
1999 RNA Society

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