Genomic organization, 5'-flanking region and chromosomal localization of the human RGS3 gene

RGS3 is the largest member of the recently discovered family of proteins (RGS proteins) that function as negative regulators of heterotrimeric G protein signaling. Despite the intense interest in RGS proteins as physiological regulators of G protein signaling, there is little understanding of the structure and regulation of mammalian RGS genes. Using long distance PCR, we amplified and characterized the entire coding and 5'-untranslated region (5'-UTR) of the human RGS3 gene. The coding region of the human (RGS3) gene spans 14.7 kb and contains 6 exons and the 5'-UTR spans 3.2 kb and contains 2 exons. Mapping of the exons revealed that the RGS domain, conserved among all RGS proteins, was encoded by three exons, while the unique amino terminal domain of RGS3 was encoded by a single exon. The intron locations of the human RGS3 and RGS2 genes were remarkably conserved, providing the first conceptual support for a common ancestral mammalian RGS gene. 5'-RACE analysis was used to map the transcription start site 517 bp upstream of the translational start site. Analysis of 1 kb of the 5'-flanking region revealed the presence of many potential regulatory elements, the presence of an initiator (Inr) element overlapping the transcription start site, and the absence of a TATA or CCAAT box at usual positions. By radiation hybrid mapping, the human RGS3 gene was assignett to human chromosome 9q31-q33. This study is the first to elucidate the structure, chromosomal location and regulatory sequences of the RGS3 gene. (NIH HL41071, DK25295).