Cloning and chromosomal localization of the human A2b adenosine receptor gene (ADORA2B) and its pseudogene

To determine the chromosomal localization of the human A2b adenosine receptor, the corresponding genomic clone was isolated and used as a probe for fluorescence in situ hybridization to metaphase chromosomes. Partial sequence analysis of the A2b gene (AD-ORA2B) revealed an intron that interrupted the coding region corresponding to the second intracellular loop similar to that reported for A1 and A2a adenosine receptor genes. A pseudogene for the A2b receptor was also identified; it exhibited 79% identity to the A2b adenosine receptor cDNA coding sequence and contained multiple deletions, point mutations, and frame shifts and two in-frame stops. These changes would result in the inability to encode a functional receptor. The genomic clones were utilized to localize the A2b receptor to chromosome 17p12 and the A2b pseudogene to chromosome 1q32.