title: Identification of a single nucleotide change in a mutant gene for hypoxanthine-guanine phosphoribosyltransferase (HPRT Ann Arbor).
abstract: HPRT Ann Arbor is a variant of hypoxanthine (guanine) phosphoribosyl-transferase (HPRT: EC 2.4.2.8), which was identified in wo brothers with hyperuricemia and nephrolithiasis. In previous studies, this mutant enzyme was characterized by an increased Km for both substrates, a normal Vmax, a decreased intracellular concentration of enzyme protein, a normal subunit molecular weight and an acidic isoelectric point under native isoelectric focusing conditions. We have cloned a full-length cDNA for HPRT Ann Arbor and determined its complete nucleotide sequence. A single nucleotide change (T----G) at nucleotide position 396 has been identified. This transversion predicts an amino acid substitution from isoleucine (ATT) to methionine (ATG) in codon 132, which is located within the putative 5'-phosphoribosyl-1-pyrophosphate (PRPP)-binding site of HPRT.
mesh_terms: D001483:Base Sequence; D004247:DNA / Q000235:genetics; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics*; D007525:Isoelectric Focusing; D009154:Mutation; D012150:Polymorphism, Restriction Fragment Length
chemical_list: D004247:DNA; D007041:Hypoxanthine Phosphoribosyltransferase