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

In order to study the mechanism of tumor cell surface antigen shedding, galactosyltransferase levels were compared in 5 spontaneously metastasizing and 3 nonmetastasizing rat mammary tumors. The enzyme activity both with or without exogenous acceptors was higher in the metastasizing group. This difference did not seem to be due to the variation in levels of degrading enzymes such as pyrophosphatase or beta-galactosidase found in these tumors. Little difference in the biochemical properties of the enzyme was found between the two groups. Most of the enzyme activity (60-70%) was recivered in the microsomal frctosyltransferase was assayed in "purified" plasma membrane fractions, 70% of the activity was associated with the plasma membrane vesicles, in which the enzyme was enriched by factors of 10-40. The number of galactose acceptor sites on the plasma membranes increased in parallel to the metastasizing capacity, indicating the presence of larger numbers of incomplete glycopeptides on their cell surfaces. These findings seemed to indicate that the greater turnover of glycoprotein in the spontaneously metastasizing tumor cell surface was caused by the shedding of surface antigens into the systemic circulation of the host.
 ...
PMID:Galactosyltransferase activity in metastasizing and nonmetastasizing rat mammary carcinomas and its possible relationship with tumor cell surface antigen shedding. 83 75

K1 is a monoclonal antibody that reacts with a cell surface antigen (CAK1) found in human mesothelia and nonmucinous ovarian tumors. In this article, the characteristics of the CAK1 antigen have been examined in detail. Using immunofluorescence microscopy, we have found that the CAK1 signal is removed from the cell surface by treatment with proteases or by phosphatidylinositol-phospholipase C, but not by neuraminidase and beta-galactosidase. The phosphatidylinositol-phospholipase C-released material was found to contain the CAK1 antigen which was detected by a competition radioimmunoassay. The phosphatidylinositol-phospholipase C-released CAK1 antigen was examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting and found to be approximately 40 kDa protein. The CAK1-K1 antibody complex remains on the cell surface and is poorly internalized, as shown by an acid wash immunofluorescence internalization assay. An immunotoxin composed of K1 and Lys-PE40, a mutant form of Pseudomonas exotoxin lacking the cell binding domain, was not cytotoxic, supporting the conclusion that the CAK1-K1 antibody complex is not internalized. However, an immunotoxin composed of K1 and native Pseudomonas exotoxin was selectively cytotoxic to cells expressing the CAK1 antigen. This cytotoxicity is due to the fact that domain I of Pseudomonas exotoxin promotes internalization of antigens which are not internalized or bound to antibody alone. Our results suggest that CAK1 is a polypeptide that is expressed on mesothelial cells and many ovarian cancers, and that K1 may be useful as a targeting agent for the immunotherapy of human ovarian cancer.
 ...
PMID:Characterization of the antigen (CAK1) recognized by monoclonal antibody K1 present on ovarian cancers and normal mesothelium. 172 78

The number of gene assignments to human chromosome 20 has increased slowly until recently. Only seven genes and one fragile site were confirmed assignments to chromosome 20 at the Ninth Human Gene Mapping Workshop in September 1987 (HGM9). One fragile site, 13 additional genes, and 10 DNA sequences that identify restriction fragment length polymorphisms (RFLPs), however, were provisionally added to the map at HGM9. Five mutated genes on chromosome 20 have a relation to disease: a mutation in the adenosine deaminase gene results in a deficiency of the enzyme and severe combined immune deficiency; mutations in the gene for the growth hormone releasing factor result in some forms of dwarfism; mutations in the closely linked genes for the hormones arginine vasopressin and oxytocin and their neurophysins are probably responsible for some diabetes insipidus; and mutations in the gene that regulates both alpha-neuraminidase and beta-galactosidase activities determine galactosialidosis. The gene for the prion protein is on chromosome 20; it is related to the infectious agent of kuru, Creutzfeld-Jacob disease, and Gertsmann-Straussler syndrome, although the nature of the relationship is not completely understood. Two genes that code for tyrosine kinases are on the chromosome, SRC1 the proto-oncogene and a gene (HCK) coding for haemopoietic kinase (an src-like kinase), but no direct relation to cancer has been shown for either of these kinases. The significance of non-random loss of chromosome 20 in the malignant diseases non-lymphocytic leukaemia and polycythaemia vera is not understood. Twenty-four additional loci are assigned to the chromosome: five genes that code for binding proteins, one for a light chain of ferritin, genes for three enzymes (inosine triphosphatase, s-adenosylhomocysteine hydrolase, and sterol delta 24-reductase), one for each of a secretory protein and an opiate neuropeptide, a cell surface antigen, two fragile sites, and 10 DNA sequences (one satellite and nine unique) that detect RFLPs.
 ...
PMID:The map of chromosome 20. 307 44

The serum glycoprotein alpha 2-macroglobulin can be converted into a potent macrophage-activating factor that promotes the Fc gamma receptor-mediated phagocytosis of macrophages, through modification of the sugar moiety with liposome-treated B-cell glycosidase(s). This paper discusses the activation mechanism of B-cell membranous glycosidase by liposomes using mouse splenic B cells. B-cell membranous beta-galactosidase and beta-N-acetylglucosaminidase were significantly activated by liposome treatment, and this process can be regulated by trypsin-sensitive protein. To clarify the contribution of trypsin-sensitive protein to enzyme activities, the B-cell surface antigen receptor was studied. With the addition of a Fab' fragment of anti-mouse IgM but not IgD antibody, the activation of both glycosidases induced by liposomes was significantly inhibited and was essentially the same as that of saline-treated glycosidase activities. Consequently, interactions of liposomes with cell-surface IgM may cause B-cell membranous glycosidase activation. A significant decrease in membrane fluidity, particularly near the membrane surface rather than deep within the membrane, was observed in liposome-treated B cells using electron spin resonance. Liposomes would thus appear to interact with B cells via cell-surface IgM, with a consequent decrease in membrane fluidity, as well as the activation of B-cell membranous glycosidases, causing alpha 2-macroglobulin to be converted into a macrophage activating factor.
 ...
PMID:Modification of alpha 2-macroglobulin into a macrophage-activating factor through the action of liposome-stimulated B-cell membranous glycosidases. 759 Aug 82

Amplification of multipotential stem cells, with or without ex vivo gene transfer, offers the potential for their use for beneficial repopulation of a host in which there is specific cellular deficiency or functional impairment. The aims of the current study were to immunoselect, genetically mark, and determine the fate of fibroblastic progenitor cells in vivo. A monoclonal antibody, HOP-26, which has high reactivity with a cell surface antigen present on human osteoprogenitors in bone marrow fibroblast populations, was used to select these cells by immunopanning. Following culture in 10% FCS in alphaMEM containing ascorbate-2-phosphate and dexamethasone the amplified cells expressed the osteoblast phenotype as determined by expression of osteocalcin protein determined immunohistochemically, and Type I collagen and osteocalcin mRNA expressions determined by RT-PCR analysis. The selected cells were genetically labeled using a murine leukemia virus (MuLV) encoding a reporter gene (lacZ) with a selective marker gene (neo(r)) using a triple transient transfection protocol. Transfected cells were implanted in CB17 scid/scid mice by local subcutaneous injection over the calvariae. Localization of the genetically marked cells within the calvarial tissues was detected by beta-galactosidase histochemistry and immunocytochemistry. Genetically marked cells were observed within the periosteal layer in close association with the osteoblast layer, covering mineralized bone surfaces and within bone osteoid at 5 and 7 days after injection. This study demonstrates the successful selection, expansion, and retroviral-marking of human osteoprogenitors and their migration and localization within calvariae of SCID mice following in vivo implantation. These basic studies indicate the migration of these cells to skeletal sites and support possibilities for future uses of human osteoprogenitors in therapy of bone deficiency diseases and the potential for development of gene therapy procedures in these conditions.
 ...
PMID:Retroviral marking of human bone marrow fibroblasts: in vitro expansion and localization in calvarial sites after subcutaneous transplantation in vivo. 1116 57