Structure of the human gene encoding the beta-adrenergic receptor kinase

The beta-adrenergic receptor kinase (beta ARK) specifically phosphorylates the agonist-occupied forms of the beta 2-adrenergic receptor and related G protein-coupled receptors. beta ARK is one of the best characterized members of a growing family of G protein-coupled receptor kinases. In this article we report the isolation and structural organization of the human beta ARK gene. The gene spans approximately 23 kilobases and is composed of 21 exons interrupted by 20 introns. Exon sizes range from 52 bases (exon 7) to over 1200 bases (exon 21), intron sizes from 68 bases (intron L) to 10.8 kilobases (intron A). The splice sites for donor and acceptor were in agreement with the canonical GT/AG rule. Functional regions of beta ARK are described with respect to their location within the exon-intron organization of the gene. Primer extension and RNase protection assays suggest a major transcription start site approximately 246 bases upstream of the start ATG. Sequence analysis of the 5'-flanking/promoter region reveals many features characteristic of mammalian housekeeping genes, i.e. the lack of a TATA box, an absent or nonstandard positioned CAAT box, high GC content, and the presence of Sp1-binding sites. The extraordinarily high GC content of the 5'-flanking region (> 80%) helps define this region as a CpG island that may be a principal regulator of beta ARK expression.