title: Transferrin binds specifically to pachytene spermatocytes.
abstract: We have examined the secretion and binding of transferrin to rat testicular cells. The only testicular cells found to secrete transferrin were the Sertoli cells (control 549 +/- 6; FSH 1020 +/- 17 ng/day X 10(6) cells, mean +/- SEM). The Sertoli cells also contained specific binding sites for transferrin with a Kd of 2.0 X 10(-9)M. Of the other testicular cells examined only fractions rich in pachytene spermatocytes possessed specific transferrin-binding sites. Late pachytene spermatocytes (97% pure) bound [125I]iodotransferrin with a similar affinity as Sertoli cells (Kd 1.7 X 10(-9)M). Fractions of early and mid pachytene spermatocytes contained transferrin-binding sites with a higher affinity (Kd 0.3 X 10(-9)M). This is the first report of a protein that has specific binding sites on germ cells.
mesh_terms: D000818:Animals; D007700:Kinetics; D008297:Male; D051381:Rats; D012708:Sertoli Cells / Q000378:metabolism; D013090:Spermatocytes / Q000378:metabolism*; D013094:Spermatozoa / Q000378:metabolism*; D014168:Transferrin / Q000378:metabolism*
chemical_list: D014168:Transferrin