Yeast beta- and beta'-coat proteins (COP). Two coatomer subunits essential for endoplasmic reticulum-to-Golgi protein traffic.

To understand better the role of non-clathrin coat proteins in membrane traffic, we have cloned and characterized two essential genes encoding subunits of the yeast coatomer, SEC26 and SEC27. Sec26p is a 109-kDa protein that shares 43% sequence identity with mammalian beta-coat protein (beta-COP). Sec26p-depleted cells accumulate endoplasmic reticulum (ER) ...
forms of secretory precursor proteins, and growth ceases after a dramatic accumulation of ER membranes. Sec26p overproduction partially suppresses sec27-1, a new mutant that shows a temperature-sensitive defect in ER-to-Golgi transport. The SEC27 gene was cloned, and the sequence predicts a 99.4-kDa protein with 45% sequence identity to mammalian beta'-COP. Our sequence data support a two-domain model for the SEC27 protein: a conserved amino-terminal domain, composed of five WD-40 repeats similar to those found in beta-subunits of trimeric G proteins, and a less conserved carboxyl-terminal domain. Genetic interactions connect sec27-1 and sec21-1 (coatomer gamma subunit) with the ARF1 and ARF2 genes and with the SEC22, BET1, and BOS1 genes, which encode membrane proteins involved in ER-to-Golgi transport.
Mesh Terms:
Amino Acid Sequence, Animals, Biological Transport, Cloning, Molecular, Coatomer Protein, Endoplasmic Reticulum, Fungal Proteins, Golgi Apparatus, Membrane Proteins, Molecular Sequence Data, Mutation, Saccharomyces cerevisiae, Sequence Analysis, DNA, Sequence Homology, Amino Acid
J. Biol. Chem.
Date: Sep. 30, 1994
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