We have cloned the mouse CCK-A receptor gene (Cckar), determined its nucleotide sequence, and analyzed its expression. The receptor protein is encoded in five exons distributed over 9 kb of genomic DNA. Intron/exon borders were determined by comparing the genomic nucleotide sequence with the mouse cDNA sequence obtained by reverse transcriptase polymerase chain reaction. RNase protection analysis ofCckartranscripts revealed the presence of a splice acceptor site 200 bp upstream of the translational start codon, indicating that the promoter is associated with a non-translated exon at an upstream site. The second coding exon contains a rarely used alternative splice site that would result in the production of a truncated, 48 amino acid protein.Cckaris widely expressed in the gastrointestinal system (pancreas, gallbladder, intestine, colon and stomach), as well as in brain and kidney.