Interaction of Proteins of Epididymal Origin with Spermatozoa

Abstract

The present work was devoted to the study of certain aspects of the interaction of rat specific epididymal proteins (SEP) with spermatozoa. The amounts of SEP bound to rat sperm from several regions of the epididymis were quantified using a micro-complement fixation technique. Sperm from the caput, corpus, and cauda epididymidis contained increasing amounts of both total SEP and of protein D-E on their surface. Incubations, either in utero or in vitro in conditions similar to those known to favor capacitation, resulted in a substantial loss of SEP from spermatozoa. Exposure of corpus and caudal spermatozoa to solutions containing 0.2 to 0.25 M salt reduced the amount of bound SEP to the level found in caput sperm whereas this treatment had no effect on SEP bound to caput spermatozoa.