Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Molecular analysis of the human beta-galactosidase gene revealed six different mutations in 10 of 11 Japanese GM1-gangliosidosis patients. They were the only abnormalities in each allele examined in this study. A 165-nucleotide duplication (positions 1103-1267) was found in two infantile patients, producing an abnormally large mRNA; one patient was probably a homozygote, and the other was a heterozygote of this mutation. The other two infantile patients had different mutations; a 123 Gly(GGG)----Arg(AGG) mutation in one patient and a 316 Tyr(TAT)----Cys(TGT) mutation in the other. A 201 Arg(CGC)----Cys(TGC) mutation, eliminating a BspMI site, was detected in a late-infantile/juvenile patient; the restriction-site analysis of amplified genomic DNA confirmed his heterozygosity for this mutation. A 51 Ile(ATC)----Thr(ACC) mutation was found in all five adult/chronic patients examined in this study. It created a SauI site, and restriction-site analysis confirmed that four patients were homozygous mutants. The other was a compound heterozygote for this mutation and another 457 Arg(CGA)----Gln(CAA) mutation. These mutant genes expressed markedly decreased or completely deficient enzyme activities in beta-galactosidase-deficient human fibroblasts transformed by adenovirus-SV40 recombinants. We conclude that gene mutations are heterogeneous in GM1-gangliosidosis but that the 51 Ile(ATC)----Thr(ACC) mutation is common among the Japanese adult/chronic cases. Genotype-phenotype correlations in GM1-gangliosidosis are briefly discussed.
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PMID:Human beta-galactosidase gene mutations in GM1-gangliosidosis: a common mutation among Japanese adult/chronic cases. 190

DNA sequence analysis of dtxR has shown that the M(r) 25,316 regulatory protein contains a single cysteine residue at position 102. DtxR readily forms inactive disulfide-linked dimers. We have used saturation site-directed mutagenesis of the cysteine codon (TGC) at position 102 in order to determine the role of this residue in metal ion binding. We show that the insertion of amino acids other than cysteine or aspartic acid into this position abolishes DtxR function both in vitro and in recombinant Escherichia coli DH5 alpha:lambda RS45toxPO/lacZ. Only those mutant alleles in which the TGC codon for Cys-102 was replaced by either TGT (Cys) or GCA (Asp) were found to direct the expression of active forms of DtxR that regulate the expression of beta-galactosidase from the toxPO/lacZ transcriptional fusion.
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PMID:Cysteine-102 is positioned in the metal binding activation site of the Corynebacterium diphtheriae regulatory element DtxR. 837 26