Identification and characterization of goose prolactin receptor.

Prolactin receptor (PRLR) is a single transmembrane protein through which prolactin plays a wide variety of physiological roles in vertebrates. To understand its role in goose behavior, we cloned the gene of goose PRLR (gPRLR) in the Siji goose, a domestic goose with strong broodiness in China, and examined its expression level in different organs of adult geese. Our results showed that gPRLR cDNA contained 443 bp 5' untranslated region, 2,496 bp coding sequence that presumably comprises at least 14 exons, and 220 bp 3' untranslated region. The predicted goose PRLR contained 831 amino acids and exhibited identities of 87.7, 85.2, and 84.8% with chicken, pigeon, and turkey PRLR, respectively. It comprised a signal peptide of 24 amino acids at the N terminus, 2 ligand binding regions of the extracellular domain, each containing 2 pairs of cysteine residues and a pentapeptide of 5 amino acids known as WS motif (Tpr-Ser-any amino acid-Tpr-Ser), the 2 typical features highly conserved in the members of class 1 cytokine receptor superfamily. Phylogenetic analysis revealed that the goose PRLR is highly conserved during evolution. In addition, we discovered 2 other alternative splicing transcripts of gPRLR. One is generated by missing the last 95 bp of the first 330 bp of the 3,159 bp cDNA. The other is produced by an alternative transcription initiation, leading to creation of a novel first exon that is directly spliced to the third exon. Reverse transcription PCR analyses show that the gPRLR mRNA is widely expressed in the testis, seminal duct, ovary, oviduct, kidney, large intestine, and small intestine.