Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.20 (alpha-glucosidase)
 4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cytolytic lymphocytes contain specialized lytic granules whose secretion during cell-mediated cytolysis results in target cell death. Using serial section EM of RNK-16, a natural killer cell line, we show that there are structurally distinct types of granules. Each type is composed of varying proportions of a dense core domain and a multivesicular cortical domain. The dense core domains contain secretory proteins thought to play a role in cytolysis, including cytolysin and chondroitin sulfate proteoglycan. In contrast, the multivesicular domains contain lysosomal proteins, including acid phosphatase, alpha-glucosidase, cathepsin D, and LGP-120. In addition to their protein content, the lytic granules have other properties in common with lysosomes. The multivesicular regions of the granules have an acidic pH, comparable to that of endosomes and lysosomes. The granules take up exogenous cationized ferritin with lysosome-like kinetics, and this uptake is blocked by weak bases and low temperature. The multivesicular domains of the granules are rich in the 270-kD mannose-6-phosphate receptor, a marker which is absent from mature lysosomes but present in earlier endocytic compartments. Thus, the natural killer granules represent an unusual dual-function organelle, where a regulated secretory compartment, the dense core, is contained within a pre-lysosomal compartment, the multivesicular domain.
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PMID:The lytic granules of natural killer cells are dual-function organelles combining secretory and pre-lysosomal compartments. 227 62

Viscum album extracts (Helixor) were investigated for their potency to influence natural killer cell (NK) cytotoxicity of human peripheral blood mononuclear cells (PBMC) in vitro. The samples investigated were unable to enhance NK cytotoxicity in PBMC/tumor cell co-cultures by direct short-term mediation but NK cytotoxicity of human PBMC was strongly stimulated when PBMC were pre-incubated for 72 h with a partly purified fraction (HM-BP) derived from extracts of V. album mali. Stimulation of NK cytotoxicity was not dependent from age and sex of PBMC donors and was directed against highly as well as moderately NK-sensitive human tumor cells. The responding effector cells were identified as monocytes/macrophages and stimulation of the NK cytotoxicity of these cells was not based on increased proliferation. The active component in the HM-BP fraction has a molecular weight of about 1000 Da or smaller and correlates with the structural criteria of an oligosaccharide. The activity was completely abrogated when the active fraction was treated with endoglycosidase F or alpha-glucosidase. Partial inactivation was observed after treatment with endoglycosidase D or hemicellulase. Moreover, the active fraction induced a reduction in tumor take incidence and tumor development in mice when applied before and after tumor challenge.
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PMID:Activation of natural killer cell cytotoxicity of human blood monocytes by a low molecular weight component from viscum album extract. 262 9