CLONING, SEQUENCE AND CHARACTERIZATION OF THE HUMAN AMPD2 GENE - EVIDENCE FOR TRANSCRIPTIONAL REGULATION BY 2 CLOSELY SPACED PROMOTERS

AMP deaminase (AMPD) is manifest through a multigene family in higher eukaryotes, including man. The human AMPD1 and AMPD3 genes have been c loned and partially characterized. This study describes the cloning, c hromosomal localization, partial sequence and characterization of the human AMPD2 gene. Composed of nineteen exons and eighteen intervening sequences spanning nearly 14 kb of genomic DNA, the human AMPD2 gene i s positioned on the short arm of chromosome 1 near the p13.3 boundary, Two alternative 5' exons (1A and 1B) are remotely located upstream, w hereas the other seventeen are compressed into the 3' terminal one-hal f of the gene. Transient transfections of human retinal pigment epithe lial (RPE) cells using heterologous constructs containing 5' flanking and 5' untranslated sequences cloned upstream of a luciferase reporter gene show that promoter activities are associated with exons 1A and 1 B. Inspection of genomic DNA sequence reveals that AMPD2 promoter regi ons lack readily identifiable TATA boxes and are G + C-rich, particula rly in the region of multiple transcription initiation sites in exon 1 A. The regulation and evolution of the entire human AMPD multigene fam ily are discussed.