Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: KEGG:D03345 (beta-Galactosidase)
 434 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The role of the surrounding membrane structure on the binding characteristics of the insulin receptor was studied by using several digestive enzymes. The effects observed with particulate membrane preparations are compared with those from soluble receptor preparations. beta-Galactosidase and neuraminidase had no effect on insulin binding to either particulate or soluble receptors from human placentae. Exposure to 2 units of phospholipase C/ml increased insulin binding to particulate membranes, but was without effect on the soluble receptor preparation. The increase in binding to particulate membranes was shown to be due to an increase in apparent receptor number. After 5 min exposure to 500 microgram of trypsin/ml there was an increase in insulin binding to the particulate membrane fraction, owing to an increase in receptor affinity. After 15 min exposure to this amount of trypsin, binding decreased, owing to a progressive decrease in receptor availability. In contrast, this concentration of trypsin had no effect on the solubilized receptor preparation. Because of the differential effects of phospholipase C and trypsin on the particulate compared with the solubilized receptor preparations, it is concluded that the effects of these enzymes were due to an effect on the surrounding membrane structure. Changes in receptor configuration due to alterations within the adjoining membrane provide a potential mechanism for mediating short-term alterations in receptor function.
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PMID:The effects of digestive enzymes on characteristics of placental insulin receptor. Comparison of particulate and soluble receptor preparations. 10 Jan 6

Phenylhydrazine (Phz) is a powerful hemolytic agent which has several effects on both normal and G6PD deficient red blood cells (RBCs). We have studied the mechanism of removal of Phz-damaged human RBCs by murine macrophages. Phagocytosis of Phz-treated RBCs was found to be 50 RBCs/100 mac as compared to 2 RBCs/100 mac of the controls. EGTA and sodium azide inhibited the phagocytosis, indicating a requirement for both calcium ions and energy. Incubation of macrophages with sugars such as D-galactose or D-mannose reduced phagocytosis of Phz-treated RBCs by up to 60%, indicating the involvement of a macrophage lectin-like receptor in the recognition of Phz-treated RBCs. The presence of serum in the phagocytosis assay did not affect either phagocytosis of Phz-treated RBCs or inhibition by sugars. beta-Galactosidase, but not neuraminidase, treatment of RBCs caused a significant inhibition in phagocytosis of Phz-treated RBCs. These results suggest that galactosyl residues are exposed on RBC membrane during oxidation, probably not as a result of desialization. We conclude that Phz-treated RBCs are detected as damaged cells mainly due to sugar changes on their membrane, which are directly recognized by lectin-like receptors on the macrophages.
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PMID:A lectin-like receptor on murine macrophage is involved in the recognition and phagocytosis of human red cells oxidized by phenylhydrazine. 210 24

Lysosomal neuraminidase and beta-galactosidase are present in a complex together with a 32-kDa protective protein. This complex has been purified and the different components have been dissociated using potassium isothiocyanate (KSCN) treatment. beta-Galactosidase remains catalytically active, but neuraminidase loses its activity upon dissociation. The inactive dissociated neuraminidase was purified by removing the remaining non-dissociated beta-galactosidase/protective protein complex using beta-galactosidase-specific affinity chromatography. The dissociated neuraminidase material shows two major polypeptides on SDS-PAGE with an apparent molecular mass of 76 kDa and 66 kDa. Subsequently the 32-kDa protective protein was dissociated from the beta-galactosidase/protective protein complex, and purified. Antibodies raised against the dissociated inactive neuraminidase preparation specifically immunoprecipitate the active neuraminidase present in the complex with beta-galactosidase and protective protein. By immunoblotting evidence is provided that the 76-kDa protein is a subunit of neuraminidase which, in association with the 32-kDa protective protein, is essential for neuraminidase activity.
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PMID:Purification and partial characterization of lysosomal neuraminidase from human placenta. 310 33

Previous histochemical and biochemical studies have documented the presence of carbohydrate-containing molecules in the retinal interphotoreceptor matrix (IPM). The lectin peanut agglutinin (PNA), which preferentially binds galactose-containing carbohydrates, especially galactose-galactosamine linkages, selectively labels cone photoreceptor-associated domains of the IPM ('cone matrix sheaths') in a variety of vertebrate retinas. In the studies described here, the nature of these PNA-binding components was investigated by monitoring the effects of proteolytic and glycosidic enzymes on binding of the lectin in the retina and IPM. All proteolytic enzymes tested cause a marked reduction in PNA-binding to cone matrix sheaths, suggesting that proteinaceous components are important to their organization. Exposure to O-glycanase, but not N-glycanase, markedly reduces binding of PNA to cone matrix sheaths indicating that O-linked oligosaccharides are probably responsible for its binding. Galactose oxidase treatment reduces PNA-binding throughout the retina and IPM, confirming that galactose moieties are involved in its binding. beta-Galactosidase (either before or after neuraminidase treatment) does not alter the pattern of PNA binding, suggesting that neither terminal nor penultimate beta-linked galactose residues constitute a major proportion of the lectin's binding sites in the retina. Neuraminidase treatment markedly increases the density and distribution of PNA binding throughout the retina and IPM, however, this effect appears to be, at least in part, the result of the binding of the lectin to neuraminidase molecules that become associated with tissue sections in addition to binding to carbohydrate groups unmasked by desialation. Exposure to chondroitinases causes disruption of the morphological integrity of cone matrix sheaths and slight diminution of PNA binding. Other enzymes acting on common constituents of extracellular matrices do not have similar effects. Taken together, these observations suggest that PNA-binding to cone matrix sheaths is due to the presence of glycoconjugates with galactose-containing, O-linked oligosaccharide chains.
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PMID:Enzymatic characterization of peanut agglutinin-binding components in the retinal interphotoreceptor matrix. 310 30

The turnover of lysosomal beta-galactosidase was studied in fibroblast cultures from patients with Gm1-gangliosidosis and combined beta-galactosidase and neuraminidase deficiency, which had 5-10% residual beta-galactosidase activity. beta-Galactosidase was specifically inactivated with the suicide substrate beta-D-galactopyranosylmethyl-p-nitro-phenyltriazene (beta-Gal-MNT) and from the subsequent restoration of enzyme activity in cell cultures turnover times were calculated. By using [3H]beta-Gal-MNT, the hydrolytic activity per molecule of beta-galactosidase was determined. 3H-labelled beta-D-galactopyranosylmethylamine, the precursor of [3H]beta-gal-MNT, was obtained by Raney-nickel-catalysed exchange with 3H2O. The rate of synthesis of beta-galactosidase in normal and all mutant cells tested was found to be 0.4-0.5 pmol/day per mg of cellular protein. The GM1-gangliosidosis cells tested contain the normal amount of 0.5 pmol of beta-galactosidase/mg of protein with a normal turnover time of about 10 days, but only 10% of beta-galactosidase activity per enzyme molecule. Cells with combined beta-galactosidase and neuraminidase deficiency contain only 0.3 pmol of beta-galactosidase/mg of protein with a decreased turnover time of 1 day and normal hydrolytic properties (200 nmol of 4-methylumbelliferyl galactoside/h pmol of beta-galactosidase).
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PMID:Turnover of beta-galactosidase in fibroblasts from patients with genetically different types of beta-galactosidase deficiency. 680 Mar 55