Molecular characterization, expression profile, and polymorphism of goose dopamine D1 receptor gene

Dopamine D1 receptor (DRD1) is one of the dopamine receptors with seven transmembrane domains that are coupled to the G protein. In the present study, we cloned the full coding region of DRD1 gene by the reverse transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends from the goose hypothalamus tissues. Results showed that the goose DRD1 cDNA (GenBank: KF156790) contained a 1,356 bp open reading frame encoding a protein 452 amino acid with a molecular weight of 50.52 kDa and a isoelectric point of 6.96. Bioinformatics analysis indicated that the deduced amino acid sequence was 71-98% identical to the DRD1 protein of other species, contained seven transmembrane domains and four N-glycosylation sites. A phylogenetic tree analysis revealed that the deduced goose DRD1 protein had a close genetic relationship and evolutional distance with that of duck, chicken, and zebra finch. The semi-quantitative RT-PCR analysis displayed goose DRD1 gene was widely expressed in all detected tissues, including heart, lung, liver, spleen, kidney, breast muscle, duodenum, sebum, pituitary, hypothalamus, ovary and oviduct. Eighteen single nucleotide polymorphisms were indentified in 3,169 bp length of this gene. For G90A mutation, the genotyping analysis of PCR-TspRI-RFLP showed the allele G was in dominance in all detected goose breeds, and the allele frequencies of this polymorphism were significantly different between Chinese goose breeds and foreign breeds (P<0.01). These findings will help us understand the functions of the DRD1 gene and the molecular breeding in geese.