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Updated: Jul 29, 2026

Phosphopeptide Analysis of Rodent Epididymal Spermatozoa
Published on: December 30, 2014
Restricted lateral diffusion of PH-20, a PI-anchored sperm membrane protein
B M Phelps1, P Primakoff, D E Koppel
1Department of Physiology, University of Connecticut Health Center, Farmington 06032.
Abstract:
The rate of lateral diffusion of integral membrane proteins is constrained in cells, but the constraining factors for most membrane proteins have not been defined. PH-20, a sperm surface protein involved in sperm-egg adhesion, was shown to be anchored in the plasma membrane by attachment to the lipid phosphatidylinositol and to have a diffusion rate that is highly restricted on testicular sperm, being more than a thousand times slower than lipid diffusion. These results support the hypothesis that lateral mobility of a membrane protein can be regulated exclusively by interactions of its ectodomain.
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