Scientific article

Cloning and functional characterization of mammalian homologues of the COPII component Sec23

Published inMolecular biology of the cell, vol. 7, no. 10, p. 1535-1546
Publication date1996

We screened a human cDNA library with a probe derived from a partial SEC23 mouse homologue and isolated two different cDNA clones (hSec23A and hSec23B) encoding proteins of a predicted molecular mass of 85 kDa. hSec23Ap and hSec23Bp were 85% identical and shared 48% identity with the yeast Sec23p. Affinity-purified anti-hSec23A recognized a protein of approximately 85 kDa on immunoblots of human, mouse, and rat cell extracts but did not recognize yeast Sec23p. Cytosolic hSec23Ap migrated with an apparent molecular weight of 350 kDa on a gel filtration column, suggesting that it is part of a protein complex. By immunoelectron microscopy, hSec23Ap was found essentially in the ribosome-free transitional face of the endoplasmic reticulum (ER) and associated vesicles. hSec23Ap is a functional homologue of the yeast Sec23p as the hSec23A isoform complemented the temperature sensitivity of the Saccharomyces cerevisiae sec23-1 mutation at a restrictive temperature of 34 degrees C. RNase protection assays indicated that both hSec23 isoforms are coexpressed in various human tissues, although at a variable ratio. Our data demonstrate that hSec23Ap is the functional human counterpart of the yeast COPII component Sec23p and suggest that it plays a similar role in mammalian protein export from the ER. The exact function of hSec23Bp remains to be determined.

  • Animals
  • COP-Coated Vesicles
  • Cloning, Molecular
  • DNA, Complementary/genetics
  • Fungal Proteins/ genetics
  • GTPase-Activating Proteins
  • Genetic Complementation Test
  • Humans
  • Macromolecular Substances
  • Mice/ genetics
  • Microscopy, Fluorescence
  • Microscopy, Immunoelectron
  • Molecular Sequence Data
  • Molecular Weight
  • Proteins/ genetics
  • Rats
  • Saccharomyces cerevisiae/ genetics
  • Saccharomyces cerevisiae Proteins
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Species Specificity
  • Tumor Cells, Cultured
  • Vesicular Transport Proteins
Affiliation Not a UNIGE publication
Citation (ISO format)
PACCAUD, Jean-Pierre et al. Cloning and functional characterization of mammalian homologues of the COPII component Sec23. In: Molecular biology of the cell, 1996, vol. 7, n° 10, p. 1535–1546. doi: 10.1091/mbc.7.10.1535
Main files (1)
ISSN of the journal1059-1524

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