Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.4.3 (phospholipase C)
 18,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A recombinant human prostasin serine protease was expressed in several human cell lines. Subcellular fractionation showed that this serine protease is synthesized as a membrane-bound protein while a free-form prostasin is secreted into the culture medium. Prostasin was identified in nuclear and membrane fractions. Membrane-bound prostasin can be released by phosphatidylinositol-specific phospholipase C treatment, or labeled by [(3)H]ethanolamine, indicating a glycosylphosphatidylinositol anchorage. A prostasin-binding protein was identified in mouse and human seminal vesicle fluid. Both the secreted and the membrane-bound prostasin were able to form a covalently linked 82-kDa complex when incubated with seminal vesicle fluid. The complex formation between prostasin and the prostasin-binding protein was inhibited by a prostasin antibody, heparin, and serine protease inhibitors. Prostasin's serine protease activity was inhibited when bound to the prostasin-binding protein in mouse seminal vesicle fluid. This study indicates that prostasin is an active serine protease in its membrane-bound form.
 ...
PMID:Prostasin is a glycosylphosphatidylinositol-anchored active serine protease. 1127 75

Several pathophysiological conditions, including nephrotic syndrome, are characterized by increased renal activity of the epithelial Na(+) channel (ENaC). We recently identified plasmin in nephrotic urine as a stimulator of ENaC activity and undertook this study to investigate the mechanism by which plasmin stimulates ENaC activity. Cy3-labeled plasmin was found to bind to the surface of the mouse cortical collecting duct cell line, M-1. Binding depended on a glycosylphosphatidylinositol (GPI)-anchored protein. Biotin-label transfer showed that plasmin interacted with the GPI-anchored protein prostasin on M-1 cells and that plasmin cleaved prostasin. Prostasin activates ENaC by cleavage of the gamma-subunit, which releases an inhibitory peptide from the extracellular domain. Removal of GPI-anchored proteins from the M-1 cells with phosphatidylinositol-specific phospholipase C (PI-PLC) inhibited plasmin-stimulated ENaC current in monolayers of M-1 cells at low plasmin concentration (1-4 microg/ml). At a high plasmin concentration of 30 microg/ml, there was no difference between cell layers treated with or without PI-PLC. Knockdown of prostasin attenuated binding of plasmin to M1 cells and blocked plasmin-stimulated ENaC current in single M-1 cells, as measured by whole-cell patch clamp. In M-1 cells expressing heterologous FLAG-tagged prostasin, gammaENaC and prostasin were colocalized. A monoclonal antibody directed against the inhibitory peptide of gammaENaC produced specific immunofluorescence labeling of M-1 cells. Pretreatment with plasmin abolished labeling of M-1 cells in a prostasin-dependent way. We conclude that, at low concentrations, plasmin interacts with GPI-anchored prostasin, which leads to cleavage of the gamma-subunit and activation of ENaC, while at higher concentrations, plasmin directly activates ENaC.
 ...
PMID:Prostasin-dependent activation of epithelial Na+ channels by low plasmin concentrations. 1979 56