Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.11 (CD10)
 9,792 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A comprehensive survey of 11 peptidases, all of which are markers for renal microvillar membranes, has been made in membrane fractions prepared from pig choroid plexus. Two fractionation schemes were explored, both depending on a MgCl2-precipitation step, the preferred one having advantages in speed and yield of the activities. The specific activities of the peptidases in the choroid-plexus membranes were, with the exception of carboxypeptidase M, lower than in renal microvillar membranes: those of aminopeptidase N, peptidyl dipeptidase A ('angiotensin-converting enzyme') and gamma-glutamyltransferase were 3-5-fold lower, those of aminopeptidase A and endopeptidase-24.11 were 12-15 fold lower, and those of dipeptidyl peptidase IV and aminopeptidase W were 50-70-fold lower. Carboxypeptidase M had a similar activity in both membranes. Alkaline phosphatase and (Na+ + K+)-activated ATPase were more active in the choroid-plexus membranes. No activity for microsomal dipeptidase, aminopeptidase P and carboxypeptidase P could be detected. Six of the peptidases and (Na+ + K+)-activated ATPase were also studied by immunoperoxidase histochemistry at light- and electron-microscopic levels. Endopeptidase-24.11 and (Na+ + K+)-activated ATPase were uniquely located on the brush border, and the other two peptidases appeared to be much more abundant on the endothelial lining of microvessels. Dipeptidyl peptidase IV and aminopeptidase W were also detected in microvasculature. Pial membranes associated with the brain and spinal cord also stained positively for endopeptidase-24.11, aminopeptidase N and peptidyl dipeptidase A. The immunohistochemical studies indicated the subcellular fractionation did not discriminate between membranes derived from epithelial cells (i.e. microvilli) and those from endothelial cells. The possible significance of these studies in relation to neuropeptide metabolism and the control of cerebrospinal fluid production is discussed.
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PMID:Membrane peptidases in the pig choroid plexus and on other cell surfaces in contact with the cerebrospinal fluid. 265 79

Incubation of the adrenal membranes at pH 3.5-5.6 resulted in apparent proteolysis of 140 kDa protein to yield a 70 kDa polypeptide containing an ANF-binding site, which could be photoaffinity labeled by [125I]4-azidobenzoyl monoiodo ANF-(4-28). This 70 kDa fragment was found to be disulfide-linked to the remaining segment(s) of the molecule, giving a total apparent Mr of 140,000 when not reduced. The acidic pH-dependent proteolysis was rapid even at 0 degree C, suggesting close association of an endopeptidase with ANF receptor. The proteolysis was inhibited by EDTA, but not by phenylmethanesulfonyl fluoride, N-ethylmaleimide or pepstatin, indicating that the enzyme is a metalloendopeptidase. The inhibition was reversed by ZnCl2 or MnCl2, but not CaCl2 or MgCl2. The adrenal membranes contained guanylate cyclase activity of 1.1 nmol/min/mg protein using Mn-GTP as a substrate, which could be stimulated by 0.1 microM ANF to 2.7 nmol/min/mg. The membranes showed high affinity to ANF-(1-28) and ANF-(4-28), but little affinity to the truncated peptides ANF-(5-25) and ANF-(7-23). After treatment at pH 3.5 and 0 degrees C for 15 min, the membranes retained ANF-binding activity but with broader specificity, exhibiting high affinity to all four peptides above. It was suggested that an acidic metalloendopeptidase in the adrenal membranes may be involved in ANF receptor cleavage.
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PMID:Acidic pH- and metal ion (Zn++ or Mn++)-dependent proteolysis of 140 kDa atrial natriuretic factor receptor in bovine adrenal cortex plasma membranes: evidence for membrane-bound acidic metalloendopeptidase. 289 2

A processing protease for the human immunodeficiency virus type I (HIV-I) envelope glycoprotein gp160 precursor has been purified to homogeneity from the post-nuclear membrane fraction of a human T4+ lymphocyte clone. Most of the processing activity was found to be present in the fractions of endoplasmic reticulum and Golgi apparatus of the cells. The purified enzyme has a monomeric structure with a molecular mass of 26 +/- 3 kDa, as judged by gel-permeation liquid chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing and nonreducing conditions. The purified enzyme converted gp160 to gp120 and gp41, showing a pH optimum of 6.5-7.0. Direct amino acid sequencing of the amino terminus of the product gp41 revealed that the cleavage site of gp160 was between Arg511 and Ala512. The enzyme activity was inhibited by trypsin-type protease inhibitors, but was not affected by CaCl2, MgCl2 or chelating agents. The properties of the purified enzyme are clearly distinct from those of processing proteases reported previously. Although the significance of the enzyme in vivo is not currently certain, judging from its cleavage specificity and subcellular localization, this endopeptidase appears to be a processing enzyme for the human immunodeficiency virus type I gp160 precursor protein in human T cells.
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PMID:Processing protease for gp160 human immunodeficiency virus type I envelope glycoprotein precursor in human T4+ lymphocytes. Purification and characterization. 809 9