Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.2.2.7 (heparinase)
 1,270 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Intermediate density lipoproteins (IDL) were shown to bind to high- and low-affinity binding sites on rat liver membranes. The low-affinity sites were named lipoprotein binding sites (LBS), since they bind all classes of lipoproteins. This study was undertaken to further characterize the interaction of 125I-labelled IDL with the LBS of rat liver membranes to determine the chemical nature of the LBS. We found that the binding of IDL to the LBS is insensitive to EDTA and sensitive to heparin and that it is present on plasma membranes. Also, membranes were pretreated with various enzymes that have an effect on the membrane constituents, and the activity of the LBS on these treated membranes was determined. Our results reveal that the LBS of rat liver membranes is insensitive to heparinase I, chondroitinase ABC, and phospholipase C, while it is partially sensitive to phospholipase A2 and sensitive to proteases and heat. Rat liver membrane proteins were solubilized with Triton X-100, reconstituted in liposomes, and analyzed for their ability to bind lipoproteins. 125I-labelled IDL were shown to bind to high- and low-affinity sites that are similar, in affinity and specificity, to the ones observed with intact rat liver membranes, indicating that a LBS activity is detectable on these liposomes. We found that the binding capacity of low-affinity sites in liposomes containing either no protein or containing proteins solubilized from Escherichia coli membranes is five times weaker than low-affinity sites in liposomes containing liver membrane proteins. Thus, a protein solubilized from rat liver membranes has LBS activity when reconstituted in liposomes. Taken altogether our results provide new information on the binding of IDL to the LBS and indicate that the LBS activity is in part mediated by a protein. Thus, the LBS appears to be a bona fide receptor.
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PMID:Analysis of the lipoprotein binding site of rat liver membranes. 781 47

Cellular entry of human T-cell leukaemia virus type 1 (HTLV-1) was studied by a quantitative assay system using vesicular stomatitis virus (VSV) pseudotypes in which a recombinant VSV (VSVDeltaG*) containing the gene for green fluorescent protein instead of the VSV G protein gene was complemented with viral envelope glycoproteins in trans. Most of the cell lines tested showed susceptibility to VSVDeltaG* complemented with either HTLV-1 envelope glycoproteins (VSVDeltaG*-Env) or VSV G protein (VSVDeltaG*-G), but not to VSVDeltaG* alone, indicating that cell-free HTLV-1 could infect many cell types from several species. High concentration pronase treatment of cells reduced their susceptibility to VSVDeltaG*-Env, while trypsin treatment, apparently, did not. Treatment of the cells with sodium periodate, heparinase, heparitinase, phospholipase A2 or phospholipase C reduced the susceptibility of cells to VSVDeltaG*-Env, but not to VSVDeltaG* complemented with measles virus (Edmonston strain) H and F proteins (VSVDeltaG*-EdHF), which was used as a control. Purified phosphatidylcholine also inhibited the infectivity of VSVDeltaG*-Env, but not VSVDeltaG*-G. These findings indicated that, in addition to cell surface proteins, glycosaminoglycans and phospholipids play an important role in the process of cell-free HTLV-1 entry.
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PMID:Analysis of the molecules involved in human T-cell leukaemia virus type 1 entry by a vesicular stomatitis virus pseudotype bearing its envelope glycoproteins. 1125 87

Human group IIA phospholipase A2 (hIIA PLA2) is a 14 kDa secreted enzyme associated with inflammatory diseases. A newly discovered property of hIIA PLA2 is the binding affinity for the heparan sulfate proteoglycan (HSPG) glypican-1. In this study, the binding of hIIA PLA2 to apoptotic human T cells was investigated. Little or no exogenous hIIA PLA2 bound to CD3-activated T cells but significant binding was measured on activated T cells induced to undergo apoptosis by anti-CD95. Binding to early apoptotic T cells was greater than to late apoptotic cells. The addition of heparin and the hydrolysis of HSPG by heparinase III only partially inhibited hIIA PLA2 binding to apoptotic cells, suggesting an interaction with both HSPG and other binding protein(s). Two low molecular weight HSPG were coimmunoprecipitated with hIIA PLA2 from apoptotic T cells, but not from living cells. Treatment of CD95-stimulated T cells with hIIA PLA2 resulted in the release of arachidonic acid but not oleic acid from cells and this release was blocked by heparin and heparinase III. Altogether, these results suggest a role for hIIA PLA2 in the release of arachidonic acid from apoptotic cells through interactions with HSPG and its potential implication in the progression of inflammatory diseases.
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PMID:Interaction of low molecular weight group IIA phospholipase A2 with apoptotic human T cells: role of heparan sulfate proteoglycans. 1277 89