MOLECULAR-CLONING OF A BOVINE MSH RECEPTOR WHICH IS HIGHLY EXPRESSED IN THE TESTIS

A novel G protein-coupled receptor (BDF3) was isolated from bovine gen omic DNA by a combined approach of polymerase chain reaction (PCR) and hybridization techniques. The predicted amino acid sequence is 317 am ino acids in length and displays 80% homology to the human alpha-MSH r eceptor MC1. Stably transfected into CHO-K1 cells, BDF3 mediates an in crease of intracellular cAMP-levels following incubation with NLE-alph a-MSH, a potent alpha-MSH analog. The stimulation with ACTH(1-10) is o nly moderate and gamma-MSH is ineffective. Northern blot analysis of b ovine tissues revealed that the BDF3 gene is higly expressed in the te stis as a single 2.3 kb mRNA species, suggesting an involvement of the BDF3 receptor in spermatogenesis.