Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

The nature of the molecular defect resulting in the beta-galactosidase deficiency in different forms of GM1-gangliosidosis and mucopolysaccharidosis IV B (Morquio B syndrome) was investigated. Normal and mutant cultured skin fibroblasts were labeled in vivo with [3H]leucine and immunoprecipitation studies with human anti-beta-galactosidase antiserum were performed, followed by polyacrylamide gel electrophoresis and fluorography. In Morquio B syndrome, the mutation does not interfere with the normal processing and intralysosomal aggregation of beta-galactosidase. In cells from infantile and adult GM1-gangliosidosis, 85-kDa precursor beta-galactosidase was found to be synthesized normally but more than 90% of the enzyme was subsequently degraded at one of the early steps in posttranslational processing. The residual 5-10% beta-galactosidase activity in adult GM1-gangliosidosis is 64-kDa mature lysosomal enzyme with normal catalytic properties but with a reduced ability of the monomeric form to aggregate into high molecular weight multimers. Knowledge of the exact nature of the molecular defect underlying beta-galactosidase deficiency in man may lead to a better understanding of the clinical and pathological heterogeneity among patients with different types of GM1-gangliosidosis and Morquio B syndrome.
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PMID:Processing of human beta-galactosidase in GM1-gangliosidosis and Morquio B syndrome. 642 Apr 16

Some kinetic Properties of beta-galactosidase in crude extracts of cultured fibroblasts obtained from patients with Morquio B disease, GM1-gangliosidosis and from the controls were compared. The main defect in Morquio B seems to be the lowering of enzyme affinity to the substrates, while in the case of GM1-gangliosidosis of infantile type 1 a dramatic decrease of Vmax value concomitant with normal KM value was observed. Based on these observations possible interpretations of the clinical picture are discussed.
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PMID:Kinetic properties of beta-galactosidase in Morquio B disease. 643 30

Two male patients, aged 6 and 25, both with normal intelligence and absence of neurological abnormalities, exhibited dysostosis multiplex, dwarfism, odontoid anomalies, cloudy corneas, exessive excretion of keratan sulfate, and abnormal urinary oligosaccharides. Leukocytes and fibroblasts of both patients were deficient in acid beta-galactosidase (beta-gal) and normal in N-acetylgalactosamine-6-sulfate sulfatase, the deficient enzyme in classical Morquio syndrome. The beta-gal deficiency was not due to an endogenous inhibitor, and the parents exhibited intermediate activities. Deficient beta-gal activity was observed toward p-nitrophenyl-beta-galactoside, 4-methylumbelliferyl-beta-galactoside (4 MU-beta-gal), lactose, GM1 ganglioside, keratan sulfate, and asialofetuin (ASF). Under standard assay conditions, the residual activity was similar for all substrates tested. Toward p-nitrophenyl-beta-glactoside, the mutant enzyme behaved as a Km variant.
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PMID:Morquio syndrome (mucopolysaccharidosis IV B) associated with beta-galactosidase deficiency. Report of two cases. 644 39

Morquio B disease was found in a 15-year-old Japanese boy who presented with progressive generalized skeletal dysplasia without neurological manifestations. Mild keratan sulfaturia was found, and beta-galactosidase was deficient in fibroblasts. Gene analysis revealed two mutant alleles, 83Tyr-->His (Y83H) and 482Arg-->Cys (R482C). The former expressed a low enzyme activity (2-5% of normal), and the latter expressed no detectable enzyme activity.
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PMID:Clinical and molecular analysis of a Japanese boy with Morquio B disease. 758 49

GM1 gangliosidosis and Morquio syndrome type B (MPS IVB) are inherited lyosomal storage disorders associated with deficiency of beta-galactosidase-A (beta GALA) activity. A recombinant plasmid containing a biotinylated cDNA (2.4-kb insert) encoding human beta GALA was used to localize the enzyme locus by fluorescence in situ hybridization (FISH). The human beta GALA gene was assigned to 3p21.33 by FISH.
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PMID:Assignment of human beta-galactosidase-A gene to 3p21.33 by fluorescence in situ hybridization. 769 77

Recently, techniques of molecular biology have been widely applied to child neurology, and a new aspect of the pathogenesis of neurogenetic diseases has been revealed. In this article, recent results of molecular analysis in my laboratory were briefly reviewed on hereditary beta-galactosidase deficiency. After cDNA cloning, a number of gene mutations have been identified; mainly missense mutations, such as single-base substitution, duplication, insertion, and splice site mutation. A clear phenotype-genotype correlation was established for some mutations specific to the late-onset forms of the disease. Intracellular events of mutant proteins expressed by these mutant genes were heterogeneous, and expected to be closely connected to the pathogenesis of each phenotype. On the basis of these data, a unified clinical classification was proposed for GM1-gangliosidosis and Morquio B disease, together with a new concept of "beta-galactosidosis" for the diseases with beta-galactosidase gene mutations.
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PMID:[Molecular pathology of neurogenetic diseases]. 772 58

Heterogeneous patterns of biosynthesis, posttranslational processing, and degradation were demonstrated for mutant enzymes in three clinical forms of beta-galactosidase deficiency (beta-galactosidosis): juvenile GM1-gangliosidosis, adult GM1-gangliosidosis, and Morquio B disease. The precursor of the mutant enzyme in adult GM1-gangliosidosis was not phosphorylated, and only a small portion of the gene product reached the lysosomes. The enzyme in Morquio B disease was normally processed and transported to lysosomes, but its catalytic activity was low. A common gene mutation in juvenile GM1-gangliosidosis (R201C) produced an enzyme protein that did not aggregate with protective protein in the lysosome, and was rapidly degraded by thiol proteases. This abnormal turnover was similar to that for the normal but dissociated beta-galactosidase in galactosialidosis. Protease inhibitors restored the enzyme activity in fibroblasts of this clinical form. A possible therapeutic approach is discussed for this specific type of enzyme deficiency.
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PMID:Intracellular processing and maturation of mutant gene products in hereditary beta-galactosidase deficiency (beta-galactosidosis). 811 31

Recent advances in the molecular study of beta-galactosidase deficiency (GM1-gangliosidosis and Morquio syndrome type B) are reviewed. Until now, 14 different mutations have been found in the beta-galactosidase gene in patients with this disorder. Gene mutations are heterogeneous, but common and specific mutations have been identified for three types of protracted clinical course; 51Ile-->Thr mutation for Japanese adult/chronic GM1-gangliosidosis, 201Arg-->Cys for Japanese late infantile/juvenile GM1-gangliosidosis and 273Trp-->Leu for Caucasian Morquio syndrome type B. These phenotype-specific mutant genes produce mutant proteins with significant residual enzyme activity, whereas mutant proteins associated with infantile GM1-gangliosidosis patients show complete loss of enzyme activity. The phenotypic variations of this disorder may be related to different mode of intracellular processing and turnover of mutant enzyme proteins.
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PMID:[Molecular genetics of beta-galactosidase deficiency (GM1-gangliosidosis and Morquio syndrome type B)]. 841 1

beta-galactosidosis is a lysosomal storage disorder caused by a deficiency of acid beta-galactosidase, including to autosomal recessive diseases; GM1-gangliosidosis (neurovisceral form) and Morquio B disease (skeletal form). To date, 26 different mutations in the beta-galactosidase gene have been identified in patients with beta-galactosidosis from various ethnic groups. Transient expression of the mutant genes has confirmed that mutant enzymes responsible for infantile GM1-gangliosidosis have almost no detectable beta-galactosidase activity. But the other three forms (late infantile/juvenile, adult/chronic GM1-gangliosidosis and Morquio B disease) are characterized by specific mutant enzymes with significant residual enzyme activity. Heterogeneous patterns of post-translational processing and maturation in these mutant enzymes are closely related to the phenotypic variations in beta-galactosidosis.
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PMID:[beta-galactosidosis--GM1 gangliosidosis and Morquio B disease]. 857 43

N-Acetylgalactosamine-6-sulfate sulfatase (GALNS) catalyzes the first step of intralysosomal keratan sulfate (KS) catabolism. In Morquio type A syndrome GALNS deficiency causes the accumulation of KS in tissues and results in generalized skeletal dysplasia in affected patients. We show that in normal cells GALNS is in a 1.27-MDa complex with three other lysosomal hydrolases: beta-galactosidase, alpha-neuraminidase, and cathepsin A (protective protein). GALNS copurifies with the complex by different chromatography techniques: affinity chromatography on both cathepsin A-binding and beta-galactosidase-binding columns, gel filtration, and chromatofocusing. Anti-human cathepsin A rabbit antiserum coprecipitates GALNS together with cathepsin A, beta-galactosidase, and alpha-neuraminidase in both a purified preparation of the 1. 27-MDa complex and crude glycoprotein fraction from human placenta extract. Gel filtration analysis of fibroblast extracts of patients deficient in either beta-galactosidase (beta-galactosidosis) or cathepsin A (galactosialidosis), which accumulate KS, demonstrates that the 1.27-MDa complex is disrupted and that GALNS is present only in free homodimeric form. The GALNS activity and cross-reacting material are reduced in the fibroblasts of patients affected with galactosialidosis, indicating that the complex with cathepsin A may protect GALNS in the lysosome. We suggest that the 1.27-MDa complex of lysosomal hydrolases is essential for KS catabolism and that the disruption of this complex may be responsible for the KS accumulation in beta-galactosidosis and galactosialidosis patients.
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PMID:Association of N-acetylgalactosamine-6-sulfate sulfatase with the multienzyme lysosomal complex of beta-galactosidase, cathepsin A, and neuraminidase. Possible implication for intralysosomal catabolism of keratan sulfate. 891 Apr 59


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