Sec72p contributes to the selective recognition of signal peptides by the secretory polypeptide translocation complex.
SEC72 encodes the 23-kD subunit of the Sec63p complex, an integral ER membrane protein complex that is required for translocation of presecretory proteins into the ER of Saccharomyces cerevisiae. DNA sequence analysis of SEC72 predicts a 21.6-kD protein with neither a signal peptide nor any transmembrane domains. Antibodies directed against a carboxyl-terminal peptide of Sec72p were used to confirm the membrane location of the protein. SEC72 is not essential for yeast cell growth, although an sec72 null mutant accumulates a subset of secretory precursors in vivo. Experiments using signal peptide chimeric proteins demonstrate that the sec72 translocation defect is associated with the signal peptide rather than with the mature region of the secretory precursor.
Feldheim
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D
Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California at Berkeley 94720.
Schekman
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R
D000595:Amino Acid Sequence; D000906:Antibodies; D001483:Base Sequence; D004271:DNA, Fungal / Q000737:chemistry / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005656:Fungal Proteins / Q000032:analysis / Q000096:biosynthesis / Q000378:metabolism*; D005800:Genes, Fungal; D008565:Membrane Proteins / Q000032:analysis / Q000096:biosynthesis / Q000378:metabolism*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D011499:Protein Processing, Post-Translational; D021382:Protein Sorting Signals / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins
D000906:Antibodies; D004271:DNA, Fungal; D005656:Fungal Proteins; D008565:Membrane Proteins; D010446:Peptide Fragments; D021382:Protein Sorting Signals; D011993:Recombinant Fusion Proteins; C088668:SEC72 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins