gp25L/emp24/p24 Protein Family Members of the cis-Golgi Network Bind Both COP I and II Coatomer

• Published in: The Journal of cell biology Vol. 140; no. 4; pp. 751 - 765
• Main Authors: Dominguez, Michel, Dejgaard, Kurt, Füllekrug, Joachim, Dahan, Sophie, Fazel, Ali, Paccaud, Jean-Pierre, Thomas, David Y., John J. M. Bergeron, Nilsson, Tommy
• Format: Journal Article
• Language: English
• Published: United States Rockefeller University Press 23-02-1998; The Rockefeller University Press
• Subjects: Amino Acid Sequence; Amino acids; Animals; Antibodies; Base Sequence; Binding Sites; Carrier Proteins - metabolism; Cellular biology; Cloning, Molecular; Coatomer Protein; Complementary DNA; Cytosol - chemistry; Cytosol - metabolism; DNA, Complementary - genetics; Family members; Fluorescent Antibody Technique; Freight; Frozen Sections; Golgi apparatus; Golgi Apparatus - genetics; Golgi Apparatus - metabolism; HeLa Cells; Humans; Liver; Liver - chemistry; Liver - ultrastructure; Membrane proteins; Membrane Proteins - analysis; Membrane Proteins - genetics; Membrane Proteins - metabolism; Microscopy, Electron; Molecular Sequence Data; Protein Binding; Proteins; Rats; Receptors; Saccharomyces cerevisiae Proteins; Sequence Homology, Amino Acid; Subcellular Fractions - chemistry; Subcellular Fractions - ultrastructure; Vesicular Transport Proteins
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.140.4.751

Five mammalian members of the gp25L/emp24/p24 family have been identified as major constituents of the cis-Golgi network of rat liver and HeLa cells. Two of these were also found in membranes of higher density (corresponding to the ER), and this correlated with their ability to bind COP I in vitro. This binding was mediated by a K(X)KXX-like retrieval motif present in the cytoplasmic domain of these two members. A second motif, double phenylalanine (FF), present in the cytoplasmic domain of all five members, was shown to participate in the binding of Sec23 (COP II). This motif is part of a larger one, similar to the F/YXXXXF/Y strong endocytosis and putative AP2 binding motif. In vivo mutational analysis confirmed the roles of both motifs so that when COP I binding was expected to be impaired, cell surface expression was observed, whereas mutation of the Sec23 binding motif resulted in a redistribution to the ER. Surprisingly, upon expression of mutated members, steady-state distribution of unmutated ones shifted as well, presumably as a consequence of their observed oligomeric properties.