The duality of fish gonadotropin receptors: Cloning and functional characterization of a second gonadotropin receptor cDNA expressed in the ovary andtestis of amago salmon (Oncorhynchus rhodurus)

We previously isolated a cDNA encoding a gonadotropin receptor (sGTH-R) fro m amago salmon (Oncorhynchus rhodurus) ovarian follicles. In the present st udy, we cloned a second gonadotropin receptor (sGTH-RI) from the same RNA p reparations. Overall sequence homology between sGTH-RI and sGrTH-R is 44%. The highest homology occurs with mammalian FSH receptors (49%). Functional characterization examined in COS-7 cells transiently transfected with sGTH- RI showed the largest increase in cAMP production when exposed to salmon GT H I. These results provide the first evidence in any ectothermic vertebrate , the amago salmon, of the duality of gonadotropin receptors. (C) 1999 Acad emic Press.