Structure and Tissue Distribution of Cholecystokinin-1 Receptor in Chicken

Abstract

Chicken cholecystokinin-1 receptor (chCCK1R) cDNA was isolated from a chicken brain and tissue distribution of the chCCK1R mRNA was determined by RT-PCR. The chCCK1R is composed of 429 amino acid residues and showed approximately 73% and 50% identity with those of mammalian CCK1R and CCK-2 receptor (CCK2R) at the amino acid level, respectively. In phylogenetical analysis, the chCCK1R belonged to a cluster of CCK1R and CCK-CHR, another CCK receptor cloned from chicken, was placed into a cluster of CCK2R. By RT-PCR analysis, whilst both chCCK1R and CCK-CHR mRNAs were widely expressed in the chicken tissues, the expression pattern for each receptor was slightly different. Abundant chCCK1R mRNA was observed in multiple tissues, while CCK-CHR mRNA expression was dominantly observed in the brain and proventriculus in the chicken. Taken together, chCCK1R is a potent peripheral CCKR and CCK-CHR cloned and characterized previously is classified as CCK2R in the chicken. Furthermore, mRNA expression for chicken CCKRs is possible to be regulated by tissue specific manner and that may be associated with the diverse roles of CCK and gastrin in the chicken.

Keywords

• cdna cloning
• chicken
• cholecystokinin
• receptor