Use of α- and β-subunit specific antibodies in studying interaction of hCG with Leydig cell receptors

摘要: Antisera (a/s) raised to individual α- and β-subunits of human chorionic gonadotropin (hCG) have been characterized for specificity using immunoaffinity procedures used study the disposition two subunits when intact hCG is complexed with luteinizing hormone (LH) receptor Leydig cells. Three kinds experiments were done. (a) The ability preformed hormone-antibody (H-Ab) complex bind stimulate a response; (b) a/s dissociate from its thereby terminate (c) premixed antibody compete binding labeled hCG. Although subunit specific here equipotent in (capacity Ka being very similar), their behavior once preparation or cell introduced into system was drastically different. β-subunit relative α-subunit antibody, appeared be poorly effective preventing either inhibiting continuation response. results suggest that upon interaction loses determinants β-region more rapidly compared those α-region suggesting initial should occurring through sites β-subunit. portion molecule available relatively longer time, biological response seems sensitive such as it invariably loss In system, already appears dependent time addition incubation medium. antisera totally ineffective steroidogenic if added 60 min after This would hormone-receptor formed perhaps continues change orientation result less antigenic become binding.