Rkp1/Cpc2, a fission yeast rACK1 homolog, is involved in actin cytoskeleton organization through protein kinase C, Pck2, signaling

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 (De lta rkp1) are elongated and the pck2-deletion mutant (Delta pck2) showed ab normal morphology. The double-deletion mutant (Delta rkp1 Delta pck2) showe d more aberrant cell shapes and was sensitive to high salt concentration. B oth Delta rkp1 and Delta pck2 cells were sensitive to latrunculin B (kat B) which inhibits actin polymerization. The cells expressing the human RACK1 homolog complemented the latrunculin B sensitivity of Delta rkp1 indicating that human RACK1 is a functional homolog of Rkp1/Cpc2. We propose that Rkp 1/Cpc2 may function as a receptor for Pck2 in the regulation of actin cytos keleton organization during cell wall synthesis and morphogenesis of Schizo saccharomyces pombe. (C) 2001 Academic Press.