Changes in the protein composition of rat spermatozoa during maturation in the epididymis

Abstract

Spermatozoa from the testis and cauda epididymidis were solubilized by detergent treatment and electrophoresis on SDS [sodium dodecyl sulfate] polyacrylamide gels revealed that the relative amounts of 13 detergent-extractable proteins decreased during passage of spermatozoa through the epididymis, 6 increased, whilst the remainder showed little or no change. Lactoperoxidase-catalyzed iodination of plasma membrane proteins showed that the components carrying most of the label in testicular spermatozoa had MW values of 110,000, 94,000, 84,000, 55,000 and 42,000 whereas on cauda epididymal spermatozoa the MW values were 47,000, 24,000, 17,000, 14,500 and 13,500. Substantial differences were also noted in the protein composition of rete testis fluid and cauda epididymal plasma. There could be a considerable reorganization of the molecular architecture of the plasma membrane of spermatozoa during maturation in the epididymis.