p23, a Major COPI-Vesicle Membrane Protein, Constitutively Cycles through the Early Secretory Pathway

A novel type I transmembrane protein of COPI-coated vesicles, p23, has been demonstrated to be localized mainly to the Golgi complex. This protein and p24, another member of the p24 family, have been shown to bind coatomer via their short cytoplasmic tails. Here we demonstrate that p23 continuously...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1997-10, Vol.94 (21), p.11393-11398
Main Authors: Nickel, Walter, Sohn, Kai, Bunning, Carsten, Wieland, Felix T.
Format: Article
Language:English
Subjects:
Animals
Antibodies
Binding Sites
Biological Sciences
CD8 Antigens - biosynthesis
Cell Line
Cellular biology
Coatomer Protein
COP coated vesicles
COS Cells
Endoplasmic Reticulum - metabolism
Genetic mutation
Golgi apparatus
Golgi Apparatus - metabolism
HeLa Cells
Humans
Membrane proteins
Membrane Proteins - analysis
Membrane Proteins - biosynthesis
Membranes
Proteins
Rats
Recombinant Fusion Proteins - analysis
Recombinant Fusion Proteins - biosynthesis
Secretory pathway
Transfection
Yeasts
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Summary:A novel type I transmembrane protein of COPI-coated vesicles, p23, has been demonstrated to be localized mainly to the Golgi complex. This protein and p24, another member of the p24 family, have been shown to bind coatomer via their short cytoplasmic tails. Here we demonstrate that p23 continuously cycles through the early secretory pathway. The cytoplasmic tail of p23 is shown to act as a functional retrieval signal as it confers endoplasmic reticulum (ER) residence to a CD8-p23 fusion protein. This ER localization is, at least in part, a result of retrieval from post-ER compartments because CD8-p23 fusion proteins receive post-ER modifications. In contrast, the cytoplasmic tail of p24 has been shown not to retrieve a CD8-p24 fusion protein. The coatomer binding motifs FF and KK in the cytoplasmic tail of p23 are reported to influence the steady-state localization of the CD8-p23 fusion protein within the ER-Golgi recycling pathway. It appears that the steady-state Golgi localization of endogenous p23 is maintained by its lumenal domain, as a fusion protein with the lumenal domain of CD8, and the membrane span as well as the cytoplasmic tail of p23 is no longer detected in the Golgi.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.94.21.11393