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Title
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Asc1p, a WD40-domain containing adaptor protein, is required for the interaction of the RNA-binding protein Scp160p with polysomes.
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Authors
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S.Baum,
M.Bittins,
S.Frey,
M.Seedorf.
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Ref.
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Biochem J, 2004,
380,
823-830.
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PubMed id
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Abstract
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Scp160p interacts in an mRNA-dependent manner with translating ribosomes via
multiple RNA-binding heterogeneous nuclear ribonucleoprotein K-homology (KH)
domains. In the present study, we show by protein-protein cross-linking that
Scp160p is in close proximity to translation elongation factor 1A and the WD40
(Trp-Asp 40)-repeat containing protein Asc1p at ribosomes. Analysis of a
truncation mutant revealed that the C-terminus of Scp160p is essential for
ribosome binding and that Cys(1067) at the C-terminus of Scp160p is required to
obtain these cross-links. The interaction of Scp160p with ribosomes depends on
Asc1p. In fast-growing yeast cells, nearly all Asc1p is tightly bound to
ribosomes, but it can also be present in a ribosome-free form depending on
growth conditions. The functional homologue of Asc1p, mammalian RACK1 (receptor
of activated C kinase), was previously characterized as an adaptor protein
bridging activated signalling molecules with their substrates. Our results
suggest that Scp160p connects specific mRNAs, ribosomes and a translation factor
with an adaptor for signalling molecules. These interactions might regulate the
translation activity of ribosomes programmed with specific mRNAs.
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