A 20 kDa erythrocyte membrane phosphoprotein.

A small (approximately 20 kDa) protein associated with the human erythrocyte membrane undergoes phosphorylation that is potentiated by the addition of phosphatidylinositol. It is indicated that phosphatidylinositol 4.5-bisphosphate, generated in situ during the protein phosphorylation reaction. is the effective agent. Phosphorylation of the small protein is also potentiated when isolated membranes are exposed to conditions that promote the phosphorylation of the phosphatidylinositols. It is suggested that the 20 kDa membrane protein participates in biochemical signaling in the erythrocyte.