Human hypoxanthine-guanine phosphoribosyltransferase: a single nucleotide substitution in cDNA clones isolated from a patient with Lesch-Nyhan syndrome (HPRTMidland).
We have determined the molecular basis for hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficiency in a patient, J.H., with Lesch-Nyhan syndrome. Radioimmunoassay of lysates of erythrocytes or cultured B-lymphoblasts showed that this patient had no detectable HPRT enzyme activity or HPRT protein. HPRT-specific mRNA levels were normal by Northern analysis. We created a cDNA library from mRNA isolated from cultured lymphoblasts derived from this patient. Nucleotide sequencing of full-length HPRT cDNA clones revealed a single nucleotide (nt) substitution: a T-to-A transversion at nt 389. We have designated this variant HPRTMidland. The predicted amino acid (aa) substitution in HPRTMidland is a valine to aspartic acid at aa 130. This substitution is within 2 aa of the amino acid substitution in a previously defined HPRT variant, HPRTAnn Arbor. Both mutations are within a highly conserved sequence in the putative 5-phosphoribosyl-1-pyrophosphate-binding domain. The amino acid substitution in HPRTMidland causes a significant perturbation in the predicted secondary structure of this region. The HPRTMidland mutation affects a different domain of HPRT than the HPRTFlint mutation located at 167 nt away.
Davidson
B L
BL
Department of Internal Medicine, University of Michigan Medical School, Ann Arbor 48109.
Palella
T D
TD
Kelley
W N
WN
D000225:Adenine; D000595:Amino Acid Sequence; D001402:B-Lymphocytes / Q000201:enzymology; D001483:Base Sequence; D002478:Cells, Cultured; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics*; D004912:Erythrocytes / Q000201:enzymology; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics*; D007926:Lesch-Nyhan Syndrome / Q000201:enzymology / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D013941:Thymine
D004247:DNA; D007041:Hypoxanthine Phosphoribosyltransferase; D000225:Adenine; D013941:Thymine