Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P20366 (substance P)
 21,176 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have genetically replaced the native receptor binding domain of diphtheria toxin with an extended form of substance P (SP): SP-glycine (SP-Gly). The resulting fusion protein, DAB389SP-Gly, is composed of the catalytic and transmembrane domains of diphtheria toxin genetically coupled to SP-Gly. Because native SP requires a C-terminal amide moiety to bind with high affinity to the SP receptor, the precursor form of the fusion toxin, DAB389SP-Gly, was converted to DAB389SP by treatment with peptidylglycine-alpha-amidating monooxygenase. We demonstrate that following conversion, DAB389SP is selectively cytotoxic for cell lines that express either the rat or the human SP receptor. We also demonstrate that the cytotoxic action of DAB389SP is mediated via the SP receptor and dependent upon passage through an acidic compartment. To our knowledge, this is the first reported use of a neuropeptide as the targeting ligand for a fusion toxin; and the first instance in which an inactive precursor form of a fusion toxin is converted to the active form by a posttranslational modification.
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PMID:Genetic construction and properties of a diphtheria toxin-related substance P fusion protein: in vitro destruction of cells bearing substance P receptors. 869 95

Peptidylglycine alpha-hydroxylating monooxygenase (PHM; EC 1.14.17.3) catalyses the rate-limiting step in the post-translational activation of substance P, among other neuropeptides, from its glycine-extended precursor. Comparative kinetic studies were performed, using trans-styrylacetic acid or trans-styrylthioacetic acid as known mechanism-based inhibitors, of PHM isolated from rat, horse or human blood serum. Distinctive species differences with respect to PHM inactivation were observed: the efficiency of inactivation decreased in the order of horse >> rat > human. Trans-styrylacetic acid was more active than its thioether derivative. Moreover, we studied the differential sensitivity towards mechanism-based inactivation, of soluble PHM from rat blood serum and rat brain by trans-styrylacetic acid or benzylhydrazine, as well as the membrane-associated enzymes from rat brain and heart atrium. For the heart atrium membrane PHM or the soluble PHM from blood serum, inactivation rate constants k(inact)/K(I) of approximately 100 M(-1)sec(-1) were found with trans-styrylacetic acid. However, neither of the two tested compounds, at 100 microM or 12 mM, respectively, could inactivate the soluble or membranous PHMs from rat brain during a 15-min pre-incubation period. Instead, under conditions of reversible inhibition, trans-styrylacetic acid competitively inhibited the soluble or membrane-associated brain PHM with inhibition constants K(I) = 0.6 microM and 1.0 microM, respectively. Organ-selective, time-dependent inactivation of PHM with compounds of the above types might be an important pharmacological tool to control peripheral neuropeptide activation.
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PMID:Selective mechanism-based inactivation of peptidylglycine alpha-hydroxylating monooxygenase in serum and heart atrium vs. brain. 926 22