Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.31 (beta-glucuronidase)
 7,680 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A monoclonal antibody (2C5) raised against rat liver lysosomal membranes was used to identify a 78-kD glycoprotein that is present in the membranes of both endosomes and lysosomes and, therefore, is designated endolyn-78. In cultures of rat hepatoma (Fu5C8) and kidney cells (NRK), this glycoprotein could not be labeled with [35S]methionine or with [32P]inorganic phosphate but was easily labeled with [35S]cysteine and [3H]mannose. Pulse-chase experiments and determinations of endoglycosidase H (endo H) sensitivity showed that endolyn-78 is derived from a precursor of Mr 58-62 kD that is processed to the mature form with a t1/2 of 15-30 min. The protein has a 22-kD polypeptide backbone that is detected after a brief pulse in tunicamycin-treated cells. During a chase in the presence of the drug, this is converted into an O-glycosylated product of 46 kD that despite the absence of N-linked oligosaccharides is effectively transferred to lysosomes. This demonstrates that the delivery of endolyn-78 to this organelle is not mediated by the mannose-6-phosphate receptor (MPR). Immunocytochemical experiments showed that endolyn-78 is present in the limiting membranes and the interior membranous structures of morphologically identifiable secondary lysosomes that contain the lysosomal hydrolase beta-glucuronidase, lack the MPR, and could not be labeled with alpha-2-macroglobulin at 18.5 degrees C, a temperature which prevents appearance of endocytosed markers in lysosomes. Endolyn-78 was present at low levels in the plasma membrane and in peripheral tubular endosomes, but was prominent in morphologically diverse components of the endosomal compartment (vacuolar endosomes and various types of multivesicular bodies) which acquired alpha-2-macroglobulin at 18.5 degrees C, and frequently contained substantial levels of the MPR and variable levels of beta-glucuronidase. On the other hand, the MPR was very rarely found in endolyn-containing structures that were not labeled with alpha-2-macroglobulin at the low temperature. Thus, the process of lysosomal maturation appears to involve the progressive delivery of lysosomal enzymes to various types of endosomes that may have already received some of the lysosomal membrane proteins. Although endolyn-78 would be one of the proteins added early to endosomes, other lysosomal membrane proteins may be added only to multivesicular endosomes that represent very advanced stages of maturation.
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PMID:Endolyn-78, a membrane glycoprotein present in morphologically diverse components of the endosomal and lysosomal compartments: implications for lysosome biogenesis. 265 37

During the procedures of centrifugation leukapheresis and plateletpheresis, donors occasionally experience adverse clinical reactions. The possibility of whether the activation of granulocytes and the subsequent release reactions, which may have been triggered by this extracorporeal circuit, were responsible for these adverse effects was evaluated. Six blood samples were obtained at set intervals during cytapheresis. Of these samples, four were taken directly from the donor. The remaining two were drawn from the efferent lines, i.e., those which return blood from the cytapheresis machine to the donor. Reactive oxygen species produced by granulocytes were measured by chemiluminescence (CL) using microamounts of whole blood or isolated granulocytes. Furthermore, secreted granulocyte products such as neutral proteinase elastase, which is present in plasma in a complex with alpha-1-proteinase inhibitor (E-alpha-1-PI), and lysosomal beta-glucuronidase were examined. A complete blood cell count and the values of hemoglobin, hematocrit, lactate dehydrogenase, protein, albumin, and proteinase inhibitors such as alpha-2-macroglobulin and alpha-1-proteinase inhibitor were also determined. Clinical chemical and cytologic values, with the exception of those for E-alpha-1-PI, were 10 to 17 percent lower than values before apheresis. These results can be attributed to inherent plasma volume expansion. Reduced CL was observed on the stimulation of phagocytes in the whole blood assay, as well as with stimulated granulocytes. Unstimulated granulocytes, on the other hand, showed an increased native CL. These data do not indicate a cytapheresis-mediated activation of the oxidative metabolism of granulocytes, and the concomitant discharge of proteolytic enzymes remains, therefore, of no clinical importance.
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PMID:Evaluation of granulocyte-releasing products and chemiluminescence during cytapheresis. 278 54