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)

The present work describes the detection, purification, and characterization of a serine endopeptidase with preference for a phosphoserine in the P1' position of the substrate. During probing for the enzyme in crude extracts, as well as during its 64,000-fold purification, 32P-labeled guanidovaleryl-Arg-Ala-Ser(P)-isobutyl amide (I) was used to measure the cleavage of the Ala-Ser(P) bond. With this substrate, kcat was 1.7 s-1 and Km was 30 microM at the pH optimum, 7.5. The enzyme was classified as a serine peptidase from its reaction with a set of inhibitors, among which diisopropyl fluorophosphate was effective at low (20 microM) concentration. The endopeptidase showed an Mr of 74,000 under native as well as denaturing and reducing conditions, indicating that the native enzyme consists of only one major polypeptide chain. The molecular size and inhibition profile suggested identity of this enzyme with prolyl endopeptidase (EC 3.4.21.26). This was supported by its activity against specific substrates, such as succinyl-Gly-Pro-Leu-Pro-7-amido-4-methylcoumarin (kcat = 7.2 s-1 and Km = 290 microM), and by the inhibition of the latter activity by I. Compared with the cleavage of 100 microM I, Gly-Val-Leu-Arg-Arg-Ala-Ser-Val-Ala-Gln-Leu, after phosphorylation by cAMP-dependent protein kinase, was cleaved at the Ala-Ser(P) bond at a relative rate of 0.43, while cleavage of the Ala-Ser bond of the unphosphorylated undecapeptide was undetectable, i.e. less than 0.03. The pentapeptide Arg-Arg-Pro-Ser-Val was rapidly cleaved at the Pro-Ser bond (relative rate, 2.2). Still, the cleavage of the Pro-Ser(P) bond of the corresponding phosphorylated pentapeptide was even higher (relative rate, 4.0). These data suggest that phosphorylation of a serine residue in the P1' position of at least a few substrates of prolyl endopeptidase will increase the rate of their cleavage.
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PMID:A human serine endopeptidase, purified with respect to activity against a peptide with phosphoserine in the P1' position, is apparently identical with prolyl endopeptidase. 199 35

During B- and T-cell ontogeny, extensive apoptosis occurs at distinct stages of development. Agents that increase intracellular levels of cAMP induce apoptosis in thymocytes and mature B cells, prompting us to investigate the role of cAMP signaling in human CD10+ B-precursor cells. We show for the first time that forskolin (which increases intracellular levels of cAMP) increases apoptosis in the CD10- cells in a dose-dependent manner (19%-94% with 0-1,000 microM forskolin after 48 hours incubation, IC50 = 150 microM). High levels of apoptosis were also obtained by exposing the cells to the cAMP analogue 8-chlorophenylthio-cAMP (8-CPT-cAMP). Specific involvement of cAMP-dependent protein kinase (PKA) was demonstrated by the ability of a cAMP antagonist, Rp-isomer of 8-bromo-adenosine- 3', 5'- monophosphorothioate (Rp-8-Br-cAMPS), to reverse the apoptosis increasing effect of the complementary cAMP agonist, Sp-8-Br-cAMPS. Furthermore, we investigated the expression of Bcl-2 family proteins. We found that treatment of the cells with forskolin or 8-CPT-cAMP for 48 hours resulted in a fourfold decline in the expression of Mcl-1 (n = 6, P = 0.002) compared to control cells. The expression of Bcl-2, Bcl-xL, or Bax was largely unaffected. Mature peripheral blood B cells showed a smaller increase in the percentage of apoptotic cells in response to 8-CPT-cAMP (1.3-fold, n = 6, P = 0.045) compared to B-precursor cells, and a smaller decrease in Mcl-1 levels (1.5-fold, n = 4, P = 0.014). Taken together, these findings show that cAMP is important in the regulation of apoptosis in B-progenitor and mature B cells and suggest that cAMP-increased apoptosis could be mediated, at least in part, by a decrease in Mcl-1 levels.
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PMID:Activation of the cAMP signaling pathway increases apoptosis in human B-precursor cells and is associated with downregulation of Mcl-1 expression. 1036 19

When isolated mouse fat pads were incubated with insulin or sodium orthovanadate (vanadate) for up to 4h, the intracellular leptin content was increased by insulin, while it was decreased by vanadate. Bupranolol, a beta3-adrenergic receptor antagonist, prevented both effects of vanadate, i.e., the decrease in intracellular leptin and increase in cellular cAMP content, while BRL 37344, a beta3-adrenergic receptor antagonist mimicked the action of vanadate. H-89 prevented the vanadate-induced decrease in intracellular leptin, suggesting the involvement of a cAMP-dependent protein kinase (PKA). No detectable difference in the incorporation of [3H]leucine into leptin was observed between incubations of the fat pads with and without vanadate, suggesting that the action of vanadate is independent of decreasing synthesis. Similar concentrations of MG-132, a membrane-permeable proteasome inhibitor, prevented the vanadate-induced decrease in both intracellular leptin content and leptin secretion, suggesting the involvement of the proteasome in the vanadate action. The proteasome fraction separated from the vanadate-treated fat pads increased the degradation of exogenous [125I]leptin in the presence of an ATP-regenerating system together with an ubiqutination system. The endopeptidase activity against Cbz-Leu-Leu-Glu-beta-naphthylamine also was increased by the proteasome fraction. MG-132 prevented both increased effects. The 8-Br-cAMP-treated proteasome fraction increased the degradation of the exogenous leptin. H-89 prevented the effect of 8-Br-cAMP. These results indicate that vanadate decreases the intracellular leptin content by increased degradation via a cAMP/PKA-dependent process involving proteasome activation.
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PMID:Orthovanadate decreases the leptin content in isolated mouse fat pads via proteasome activation. 1236 13