Rkp1/Cpc2, a fission yeast RACK1 homolog, is involved in actin cytoskeleton organization through protein kinase C, Pck2, signaling.

Abstract The Rkp1/Cpc2, a fission yeast RACK1 homolog, interacted with Pck2, one of the known PKC homologs, in vivo and in vitro. The rkp1 -deletion mutants (Δ rkp1 ) are elongated and the pck2 -deletion mutant (Δ pck2 ) showed abnormal morphology. The double-deletion mutant (Δ rkp1 Δ pck2 ) showed more aberrant cell shapes and was sensitive to high salt concentration. Both Δ rkp1 and Δ pck2 cells were sensitive to latrunculin B (Lat B) which inhibits actin polymerization. The cells expressing the human RACK1 homolog complemented the latrunculin B sensitivity of Δ rkp1 indicating that human RACK1 is a functional homolog of Rkp1/Cpc2. We propose that Rkp1/Cpc2 may function as a receptor for Pck2 in the regulation of actin cytoskeleton organization during cell wall synthesis and morphogenesis of Schizosaccharomyces pombe.