Binding to specific receptors on oocyte plasma membranes by serum phosvitin-lipovitellin.

Specific binding sites for the serum complex of phosvitin and lipovitellin have been shown to exist on the outer surface of rapidly growing chicken oocytes. The existence and specificity of these sites were demonstrated by competition for binding to unfixed oocyte membrane fragments and by displacement of already bound and labeled phosvitin-lipovitellin from formaldehyde-fixed membranes. Only unlabeled phosvitin-lipovitellin competed with the 125I-labeled complex for binding to the fragments of displacement of bound label; IgG isolated from egg yolks and bovine serum albumin were ineffective.