title: Binding of epididymal proteins to rat spermatozoa in vivo.
abstract: The secretion of epididymal proteins and their binding to spermatozoa in rats were examined after retrograde perfusion of the superior and inferior epididymal arteries with [35S]methionine. PAGE revealed that the pattern of radioactive proteins in the luminal fluid was markedly different from the well-characterized pattern of secretory proteins obtained by in vitro incubation of epididymal minces with labeled methionine. Of the proteins secreted into the lumen, about 1% were associated with Percoll-purified spermatozoa. More proteins were associated with the spermatozoa in the corpus epididymidis than in the caput. Sequential extraction of spermatozoa with an isotonic buffer, a high-salt buffer, Triton X-100, and SDS revealed that almost half of the radiolabeled proteins could be extracted with the isotonic buffer. The firmly bound radioactive proteins remaining, which were extracted with Triton X-100 or SDS, consisted of one major band of 25 kDa and two minor bands of 30 kDa and 32 kDa. Analysis of the sperm-associated proteins at various times after the isotope was administered indicated that tight binding of proteins to spermatozoa occurs within 3 h after isotope injection.
authors.affiliation: Department of Endocrinology and Reproduction, Faculty of Medicine, Erasmus University, Rotterdam, The Netherlands.
authors.forename: J T
authors.initials: JT
authors.lastname: Vreeburg
authors.forename: M K
authors.initials: MK
authors.lastname: Holland
authors.forename: M C
authors.initials: MC
authors.lastname: Orgebin-Crist
mesh_terms: D000818:Animals; D004822:Epididymis / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008715:Methionine / Q000378:metabolism; D008970:Molecular Weight; D011485:Protein Binding; D011506:Proteins / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013094:Spermatozoa / Q000378:metabolism*
chemical_list: D011506:Proteins; D008715:Methionine