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

Acid alpha-glucosidase (EC 3.2.1.20) was purified from human placenta and bovine testis by affinity chromatography using concanavalin A (conA) and Sephadex G 200. When added to the culture medium of human fibroblasts, the enzyme purified from bovine testis is taken up with a 200-fold higher efficiency than the enzyme from human placenta. Uptake of acid alpha-glucosidase from bovine testis is mediated by the mannose-6-phosphate receptor, whereas only a minor fraction of placental enzyme appears to be equipped with the mannose-6-phosphate recognition marker. Once internalized, both human and bovine acid alpha-glucosidase demonstrate a half-life of about 10 days in fibroblasts from control individuals and patients with different clinical forms of glycogenosis type II (Pompe's disease, acid alpha-glucosidase deficiency). Evidence is presented that the mannose-6-phosphate receptor is also present on the plasma membrane of the clonal myogenic skeletal muscle cell lines G8-1 and L6J1 (respectively from mouse and rat origin) and on cultured human skeletal muscle cells derived from a muscle biopsy. Addition of bovine testis acid alpha-glucosidase to skeletal muscle cell cultures from an adult patient with glycogenosis type II leads to complete correction of the enzyme deficiency.
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PMID:Uptake and stability of human and bovine acid alpha-glucosidase in cultured fibroblasts and skeletal muscle cells from glycogenosis type II patients. 623 28