Involvement of the transmembrane protein p23 in biosynthetic protein transport

J Cell Biol. 1997 Dec 1;139(5):1119-35. doi: 10.1083/jcb.139.5.1119.

Abstract

Here, we report the localization and characterization of BHKp23, a member of the p24 family of transmembrane proteins, in mammalian cells. We find that p23 is a major component of tubulovesicular membranes at the cis side of the Golgi complex (estimated density: 12,500 copies/micron2 membrane surface area, or approximately 30% of the total protein). Our data indicate that BHKp23-containing membranes are part of the cis-Golgi network/intermediate compartment. Using the G protein of vesicular stomatitis virus as a transmembrane cargo molecule, we find that p23 membranes are an obligatory station in forward biosynthetic membrane transport, but that p23 itself is absent from transport vesicles that carry the G protein to and beyond the Golgi complex. Our data show that p23 is not present to any significant extent in coat protein (COP) I-coated vesicles generated in vitro and does not colocalize with COP I buds and vesicles. Moreover, we find that p23 cytoplasmic domain is not involved in COP I membrane recruitment. Our data demonstrate that microinjected antibodies against the cytoplasmic tail of p23 inhibit G protein transport from the cis-Golgi network/ intermediate compartment to the cell surface, suggesting that p23 function is required for the transport of transmembrane cargo molecules. These observations together with the fact that p23 is a highly abundant component in the intermediate compartment, lead us to propose that p23 contributes to membrane structure, and that this contribution is necessary for efficient segregation and transport.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Biological Transport
  • Brefeldin A
  • CHO Cells
  • Cell Compartmentation
  • Cell Fractionation
  • Cell Polarity
  • Cloning, Molecular
  • Coatomer Protein
  • Cricetinae
  • Cyclopentanes / pharmacology
  • DNA, Complementary / genetics
  • Endoplasmic Reticulum / drug effects
  • Endoplasmic Reticulum / metabolism
  • Fluorescent Antibody Technique
  • Golgi Apparatus / drug effects
  • Golgi Apparatus / metabolism*
  • Membrane Glycoproteins*
  • Membrane Proteins / classification
  • Membrane Proteins / genetics
  • Membrane Proteins / isolation & purification
  • Membrane Proteins / metabolism*
  • Microscopy, Immunoelectron
  • Microtubules / drug effects
  • Molecular Sequence Data
  • Nocodazole / pharmacology
  • Protein Binding
  • Receptors, Cytoplasmic and Nuclear*
  • Sequence Analysis, DNA
  • Viral Envelope Proteins / metabolism

Substances

  • BHKp23 protein, mammalian
  • Coatomer Protein
  • Cyclopentanes
  • DNA, Complementary
  • G protein, vesicular stomatitis virus
  • Membrane Glycoproteins
  • Membrane Proteins
  • Receptors, Cytoplasmic and Nuclear
  • Viral Envelope Proteins
  • Brefeldin A
  • Nocodazole

Associated data

  • GENBANK/AJ001513