Figure 1.

(A) Schematic of the domain structure of α- and β′-COP. In this study, we show that the WD40 domain of β′-COP (residues 1–285) is nonessential but required for selective interactions with a KTKLL motif, whereas the α-COP WD40 domain interacts with the “classical” KKTN-motif (Eugster et al., 2000). A carboxy-terminal region of β′-COP, defined by sec27-1 (a G688D mutation) is involved in maintaining α-COP stability and coatomer integrity (see text for details). (B) Growth phenotype of α- and β′-COP mutants harboring a deletion of the respective WD40 domain. Cells were streaked onto YEPD plates and grown for 3 d at the temperatures indicated. Strains were as indicated: wild-type control strains CEN::RET1, CEN::SEC27 and mutant strains CEN::ret1Δ1-285 and CEN::sec27Δ1-285. Note that sec27Δ1-285 cells are strongly temperature sensitive.