Abstract:

 To understand PRLR’s role in duck, a novel isoform with only one ligand binding region of duck prolactin receptor gene (PRLR) was identified by rapid amplification of cDNA ends (RACE) strategy. Sequence analysis showed that the isoform was 2 535 bp long, contained 431 bp 5′ untranslated region (5′-UTR), 1 884 bp coding sequence and 220 bp 3′ untranslated region (3′-UTR) and comprises 11 exons. The predicted PRLR contained 627 amino acids (aa) and comprises a signal peptide of 24 aa at N-terminus, thus, its mature protein was 603 aa long. Different from canonical avian PRLRs with two tandemly repeated ligand binding regions within the extracellular domain, the putative protein only contained one ligand binding region, similar to the vertebrate PRLRs.The ligand binding region contained 2 pairs of cysteine residues and a pentapeptide of 5 aa known as WS motif as well, the 2 typical features of highly conserved in the members of class 1 cytokine receptor superfamily. In the meanwhile, we investigated one point mutation and one single nucleotide polymorphism (SNP) which located in 5′- and 3′-UTRs of the duck prolactin receptor respectively, and the SNP (C2 391T) in the 3′-UTR was in an extreme departure from Hardy-Weinberg equilibrium in the duck population by Chi-square test.