Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Renin is found in mouse plasma as high molecular weight forms, in addition to the fully active 40 000 dalton form. By using freshly 125 I-labelled 40 000 dalton pure submaxillary mouse renin, no binding to plasma proteins was demonstrable. However, unfolding and refolding of the labelled renin by guanidine facilitated binding to specific mouse and human plasma proteins. By using antibodies against individual human plasma proteins, the specific binding proteins were identified to be the plasma protease inhibitors: alpha2-macroglobulin, inter-alpha-trypsin inhibitor, alpha2-antithrombin. Binding was also demonstrated to alpha1- and beta1-lipoproteins, albumin and to a non trypsin binding unidentified plasma protein. No binding to 56 other tested proteins was demonstrable. It is concluded that the native 40 000 renin does not bind, but that a conformational change of the renin molecule most likely is necessary before binding occurs. It is discussed whether or not inactive or high molecular weight forms of renin in plasma are 40 000 renin bound to plasma protease inhibitors and lipoprotein.
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PMID:Renin binding proteins in plasma. Binding of renin to some of the plasma protease inhibitors, to lipoproteins, and to a non-trypsin-binding unidentified plasma protein. 42 6

We have identified and characterized an anti-human renin monoclonal antibody R1-20-5 that is selective for human active renin. R1-20-5 binds active renin with a dissociation constant (Kd) of 2.5 x 10(-7) M/l and inhibits renin enzymatic activity with an inhibitory constant (IC50) of 1.4 x 10(-8) M/l. R1-20-5 competes with a synthetic renin inhibitor for binding with renin, demonstrating further that it is binding to or close to the active site. This antibody does not bind prorenin in human plasma or recombinant prorenin expressed by L-929 fibroblasts transfected with human renin gene. Furthermore, trypsin activation of prorenin resulted in immunoreactivity of the activated prorenin toward the antibody. In addition, an immunoaffinity column of R1-20-5 coupled to Sepharose retained active renin but had a low affinity for prorenin. A sensitive and rapid solid phase radioimmunoassay for active renin was developed using a "sandwich" technique employing R1-20-5 and a second non-active site-directed monoclonal antibody to human renin. Renin levels in human plasma samples were determined by the standard enzymatic assay, and by the direct radioimmunoassay for active renin, before and after trypsin activation. Trypsin treatment of plasma resulted in parallel increases in both the plasma renin enzymatic activity and in the plasma active renin concentration as measured by the direct radioimmunoassay. Overall, plasma immunoreactive active renin concentration correlated significantly with plasma renin enzymatic activity (r = 0.96, p less than 0.001). In summary, the monoclonal antibody R1-20-5 is selective for human active renin and should be a very useful tool for studies of the active enzyme in humans.
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PMID:Characterization of a monoclonal antibody specific for human active renin. 154 51

Although heparin was reported in the 1960s to inhibit renin activity, this has not always been confirmed by other investigators. Hence, we re-examined whether heparin really inhibits renin or not. Renin activities were determined by radioimmunoassay of angiotensin I generated at pH 7.4. (i) No significant difference was found between the two kinds of plasma samples obtained with heparin and with EDTA as anticoagulant, in ARC (renin activity with addition of sheep renin substrate), TRC (ARC after activation of inactive renin by trypsin), or PRA (plasma renin activity without additional substrate). (ii) Even in higher concentrations of heparin up to 500 U/mL, neither PRA, ARC, nor TRC of plasma was affected significantly. (iii) Heparin, in concentrations up to 500 U/mL, exerted no significant effect on TRC of the media of human vascular smooth muscle cell culture. In conclusion, heparin does not exert any significant inhibitory effect on human renin nor does it affect activation of inactive renin by trypsin in the range of concentration of practical use, under the conditions employed in this study.
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PMID:Does heparin inhibit renin activity? 175 38

The authors evaluated the assay performances and clinical usefulness of a newly developed solid phase radioimmunoassay (RIA) for total renin concentration (TRC) in human plasma. The direct total renin RIA was performed by a sandwich technique with a pair of anti-human renin monoclonal antibodies. Renin activation with trypsin did not change TRC. The RIA showed satisfactory assay performances and demonstrated full compatibility with a direct RIA-kit for active renin concentration (ARC) in human plasma. The values of TRC were 105.3 +/- 8.6 pg/mL in normal subjects and 136.5 +/- 14.6 pg/mL in patients with essential hypertension. The values of TRC and the ratios of ARC to TRC were high in patients with renovascular hypertension and were low in patients with primary aldosteronism. Although the TRC value in diabetic patients was 134.4 +/- 14.8 pg/mL, the ratio of ARC to TRC was low. The RIA procedure was simple since prior purification or activation of renin was not required. These results suggest that the total renin RIA and its combined use with the active renin RIA may be helpful in understanding the renin-angiotensin system in human plasma.
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PMID:Measurement of plasma total renin by the anti-human renin monoclonal antibodies. 177 17

A 54-year-old woman was referred to our hospital for the treatment of a tumor of the right chest wall. Clinical examination revealed hypertension, hypokalemia, metabolic alkalosis, hyperaldosteronism and hyperreninemia. Computed tomography and an abdominal echogram indicated a tumor in the right phrenic area and two tumors in the retroperitoneum near the pancreas head. After the surgical resection of these tumors, the primary reninism was diminished. The pathological diagnosis of these tumors was leiomyosarcoma. Plasma active and inactive (trypsin-activated) renin activities (PRA) were 85.7 and 38.9 ng angiotensin I/ml/h, respectively. These PRA did not respond to either postural stimulation or suppression by the volume expansion. Active and inactive renin activities in a right phrenic area tumor were 208 and 32 ng angiotensin I/mg protein /h, respectively. Those of an abdominal tumor were 196 and 30 ng angiotensin I/mg protein/h, respectively. Renin mRNA identical in molecular size to that of the human kidney was identified by northern blot analysis. This is the first case report of renin producing leiomyosarcoma derived from the lung, which is characterized by relatively lower plasma prorenin concentrations.
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PMID:A case of renin producing leiomyosarcoma originating in the lung. 182 28

Most mouse inbred strains carry two renin genes, Ren-1 and Ren-2, Renin-2, the product of the Ren-2 gene, is highly expressed in the submaxillary gland. It is a renin isoenzyme 96% similar to kidney renin-1, but unglycosylated. In order to investigate if glycosylation of prorenin affects its processing and/or secretion we have introduced two potential N-linked glycosylation sites into preprorenin-2 cDNA using site-directed mutagenesis. Expression plasmids were derived from wild-type and mutant renin-2 cDNA and were transfected into AtT20 cells. Both transfected cells, expressing glycosylated or unglycosylated forms, secreted prorenin and renin by the constitutive and regulated pathways, respectively. Prorenin was correctly processed to active renin but the second maturation site was not cleaved in AtT20 cells. The comparison of glycosylated and unglycosylated renin expression showed a diminished secretion of glycosylated active renin. Prevention of glycosylation with tunicamycin resulted in an improved secretion of active renin. Moreover, the efficiency of the trypsin activation in vitro was reduced for glycosylated prorenin and it was restored when the activation was performed on mutant renin secreted from tunicamycin-treated cells. It is proposed that the bulky carbohydrates attached to prorenin constitute a steric hindrance to proteolysis by maturation enzymes.
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PMID:N-linked glycosylation affects the processing of mouse submaxillary gland prorenin in transfected AtT20 cells. 190 27

Renin messenger ribonucleic acid expression has been shown in decidual tissue and endometrium, but weakly in chorion laeve, suggesting decidua as a primary source of uteroplacental renin. We proposed to confirm active renin secretion by endometrial stromal cells and examined the effect of progesterone-induced decidualization on secretion. Separate monolayer cultures of endometrial stroma, trophoblast, and mesenchymal cells were established and maintained for 10 to 15 days. Active renin concentration was measured with radioimmunoassay for angiotensin I generation and expressed as picograms per milliliter of angiotensin I generation per 10(5) cells. Active renin concentration was high in control secretory endometrial stromal cells (513 pg/ml) compared with trophoblast (none) and mesenchymal cell cultures (74 pg/ml). Marked decrease in active renin secretion occurred in control endometrial stromal cells (days 13 to 15, 86 pg/ml), whereas progesterone-induced decidualization sustained and increased secretion (days 13 to 15, 1017 pg/ml). This renin activity was quantitatively inhibited in culture fluid assays by specific human renal renin antibody in serial dilutions. Renin activity measurements before and after trypsin activation showed the majority of renin (91.15%) in the inactive form and a smaller fraction (8.85%) in the active form. Immunohistochemistry with the use of specific human renal renin antibody confirmed the presence of renin and its stimulation by progesterone in endometrial stromal cells. Progesterone had minimal effect on mesenchymal cells. These data confirmed endometrial stromal cells as a significant source of active renin and showed that progesterone induced a marked increase in this production.
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PMID:Effect of progesterone on renin secretion in endometrial stromal, chorionic trophoblast, and mesenchymal monolayer cultures. 201 41

Synaptosomes and lysosomes of rat brain were separated by differential centrifugation and a two-step gradient centrifugation with colloidal silica-gel (Percoll). The organelles were identified by the measurement of established marker-enzymes and by electronmicroscopy. Renin activity, measured by radioimmunoassay for angiotensin I (ANG I), was localized in the synaptosomes and cathepsin D-activity was found in the lysosomal fraction. Converting-enzyme activity was present in the renin-containing synaptosomes. Part of the brain renin activity could be activated by pre-incubation with trypsin. Affinity chromatography of an organelle-enriched brain fraction was carried out using a caseinyl-sepharose column and resulted in the separation of renin from cathepsin D activity; the renin peak was inhibited by antibodies raised against rat kidney renin. We conclude, that the formation of ANG I and its activation to angiotensin II (ANG II) by converting enzyme is possible in synaptosomes. This adds further evidence to an intraneuronal synthesis of ANG I and ANG II in the brain and is in support of previous results demonstrating an intraneuronal localization of the components of the brain renin-angiotensin system.
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PMID:Localization of renin (EC 3.4.23) and converting enzyme (EC 3.4.15.1) in nerve endings of rat brain. 298 84

Renin granules were isolated from rat kidney cortex by a continuous polyvinyl-pyrrolidone-coated colloidal silica (Percoll) density gradient centrifugation. A major peak of renin activity was found at a density of 1.12-1.13 g/ml, and the specific activity of renin in the peak fraction was increased by approximately 70-fold, as compared with that in the kidney cortex homogenate. On the other hand, activities of other reference enzymes, such as succinate dehydrogenase, acid phosphatase and glucose-6-phosphatase, were not detectable in the peak fraction. When the extract of the peak fraction was applied to a pepstatin column, trypsin-activated renin could not be detected in the breakthrough fractions. These results indicate that renin granules of the rat kidney cortex contain only active renin.
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PMID:Renin granules isolated from rat kidney cortex by continuous colloidal silica (Percoll) density gradient centrifugation. 301 76

Renin heterogeneity has been described in rat kidney and plasma. In this study, we used the isoelectric focusing method to 1) characterize the adrenal renin forms in control rats, in rats on low- and high-Na diets, and in nephrectomized rats; and 2) examine their resemblance with plasma renin. Active renin (AR) and inactive trypsin-activatable renin (IR) were measured in adrenal homogenates and plasma. Aliquots were subjected to isoelectric focusing gels. Activation with trypsin (5 mg/ml) was performed before or after isoelectric focusing. Results showed that adrenal glands contained AR and IR. The content of adrenal AR increased significantly only in rats fed a low-Na diet. Following anesthesia, nephrectomy, or high-Na intake, the content of adrenal AR and IR was not significantly changed. In plasma, an inverse relationship between AR and IR was found. Adrenal glands contained six forms of AR focusing at the same pH as those of plasma AR but in different proportions. After activation of IR in adrenal glands, two additional renin forms focusing at pH 6.4 and 6.1 were found, whereas after activation of plasma IR, two peaks focusing at pH 5.9 and 4.8 were significantly enhanced. Adrenal AR forms were modified by alterations of salt and water balance differently than plasma AR. These results support the hypotheses of an endogenous production of renin forms by the adrenal gland.
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PMID:Multiple renin forms in the adrenal gland. 305 4


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