Functional interactions between the p35 subunit of the Arp2/3 complex and calmodulin in yeast

The end9-1 (arc35-1) mutant was identified as an endocytosis mutant and is a mutant allele of AXC35 that encodes a subunit of the Arp2/3 complex. As f or other mutants in the Arp2/3 complex, arc35-1 is defective for endocytosi s and organization of the actin cytoskeleton. Both defects can be suppresse d by overexpression of calmodulin. Analysis of a collection of temperature- sensitive cmd1 mutants for their ability to suppress either the endocytic d efect and/or the actin defect indicates that the two defects are tightly co upled. We demonstrate that Arc35p and Cmd1p interact and that Arc35p is req uired for cortical localization of calmodulin. This is the first report lin king Arp2/3 complex function with calmodulin through which it exercises at least one of its endocytic functions.