EN
The first description is presented of nucleotide sequence of exon 2 of caprine melatonin receptor 1b (MT2). No polymorphisms of MT2 gene were detected between high fertility and year-round estrous goat breeds and low fertility and seasonal estrous goat breeds. It is likely that exon 2 of MT2 gene is not associated with fertility or reproductive seasonality in goat breeds. The nucleotide sequence of exon 2 of MT2 gene of Jining Grey goats shows much closer phylogenetic relation to the MT2 of sheep (97%) and cattle (94%) than to that of pig (84%), human (80%) and mouse (74%). A rather high nucleotide identity (62-64%) with the melatonin receptor 1a (MT1) of goat, sheep, human and mouse was also found. The caprine MT2 contains the same NAXXY motif in transmembrane 7 as the other melatonin receptors. Both DRY and CYVCR motifs were detected just downstream from its third transmembrane domain (the same as in sheep and cattle) rather than NRY and CYICH found in other melatonin receptor groups.