Many proteins bind actin, and many other proteins bind actin-binding proteins. “Sometimes I wonder why the whole cytoplasm isn't a precipitate, because it seems that everything is interacting with everything else,” says David Drubin.
“What's missing is the time dimension,” he says. “These interactions are probably dynamic.” On page , Drubin's group identifies two budding yeast proteins that may contribute to that dynamic behavior. Cope et al. isolate actin-regulating kinase 1 (Ark1p) based on its two-hybrid interaction with the actin-binding protein Sla2p. Sequence gazing and a second screen both lead to the related p53-regulating kinase 1 (Prk1p). (Yeast lacks p53; Prk1p was named based on a screen involving ectopic expression of mammalian p53 in yeast.) Ark1p, Prk1p, and related proteins appear to define a new protein kinase family.
Both proteins localize to actin patches, which in budding yeast are involved in endocytosis (actin may provide an assembly force that...
