Evidence for the binding of a human sperm component with diaphanous protein.

The YWK-II component of human sperm membrane is related to the betaA4-amyloid precursor protein (APP) of Alzheimer's disease. A yeast 2-hybrid system was used to screen a mouse testis cDNA expression library for potential ligands capable of interacting with the extracellular domain of the YWK-II component. One of the bound proteins was identified as hDIA1, which has 96% identity with p140mDia. These proteins are members of the formin homology family and participate in cytokinesis and organization of the actin cytoskeleton. By interacting with these diaphanous proteins, the YWK-II component may be involved in germ cell differentiation and in the structural formation of the acrosome.