Bimodal Interaction of Coatomer with the p24 Family of Putative Cargo Receptors

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Science  06 Sep 1996:
Vol. 273, Issue 5280, pp. 1396-1399
DOI: 10.1126/science.273.5280.1396


Cytoplasmic domains of members of the p24 family of putative cargo receptors were shown to bind to coatomer, the coat protein of COPI-coated transport vesicles. Domains that contained dilysine endoplasmic reticulum retrieval signals bound the α-, β′-, and ϵ-COP subunits of coatomer, whereas other p24 domains bound the β-, γ-, and ζ-COP subunits and required a phenylalanine-containing motif. Transit of a CD8-p24 chimera from the endoplasmic reticulum through the Golgi complex was slowed when the phenylalanine motif was mutated, suggesting that this motif may function as an anterograde transport signal. The either-or bimodal binding of coatomer to p24 tails suggests models for how coatomer can potentially package retrograde-directed and anterograde-directed cargo into distinct COPI-coated vesicles.

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