A single binding site for dilysine retrieval motifs and p23 within the gamma subunit of coatomer.
Coatomer, the major component of the coat of COPI transport vesicles, binds both to the dilysine motif of resident membrane proteins of the endoplasmic reticulum and to the cytoplasmic domain of p23, a major type I membrane protein of COPI vesicles. Using a photocrosslinking approach, we find that under native conditions a peptide analogous to the cytoplasmic domain of p23 interacts with coatomer exclusively through its gamma subunit and shares its binding site with a KKXX retrieval motif. However, upon dissociation of coatomer, interaction with various subunits, including an alpha-, beta'-, epsilon-COP subcomplex, of the photoreactive peptide is observed. We suggest that, under physiological conditions, interaction of coatomer with both endoplasmic reticulum retrieval motifs and the cytoplasmic domain of p23 is mediated by gamma-COP.
Harter
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Biochemie-Zentrum Heidelberg, Ruprecht-Karls-Universität, Im Neuenheimer Feld 328, D-69120 Heidelberg, Germany.
Wieland
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FT
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D016466:CHO Cells; D020756:Coatomer Protein; D006224:Cricetinae; D003432:Cross-Linking Reagents; D003593:Cytoplasm / Q000378:metabolism; D004151:Dipeptides / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010777:Photochemistry; D011485:Protein Binding; D011487:Protein Conformation
D020756:Coatomer Protein; D003432:Cross-Linking Reagents; D004151:Dipeptides; D008565:Membrane Proteins; D010446:Peptide Fragments; C024575:lysyllysine