Sec53, a protein required for an early step in secretory protein processing and transport in yeast, interacts with the cytoplasmic surface of the endoplasmic reticulum.
The sec53 mutant is a conditional lethal yeast secretory mutant. At 37 degrees C, precursors to exported proteins become firmly attached to the endoplasmic reticulum membrane and are not released into the lumen in a soluble form. The accumulated precursors are insoluble in the detergent Triton X-100; however, urea, a known protein denaturant, solubilizes them. Using antibody directed against the Sec53 protein, we found that a substantial portion of the Sec53 protein is associated with the cytoplasmic surface of the endoplasmic reticulum membrane. Membrane-bound Sec53 protein is largely insoluble in Triton X-100, but the protein is effectively released from the membrane by urea. We propose that the Sec53 protein may be a member of a complex of proteins required for an early step in protein processing and transport.
Ruohola
H
H
Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510.
Ferro-Novick
S
S
D001692:Biological Transport; D004721:Endoplasmic Reticulum / Q000502:physiology*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D009154:Mutation; D011485:Protein Binding; D011498:Protein Precursors / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000502:physiology*; D012995:Solubility
D005656:Fungal Proteins; D008565:Membrane Proteins; D011498:Protein Precursors