Renin Release from Renin Granules in the Dog

1978 ◽  
Vol 55 (1) ◽  
pp. 11-14 ◽  
Author(s):  
S. Funakawa ◽  
T. Higashio ◽  
K. Yamamoto
Keyword(s):  
Membrane Fraction ◽  
Renin Activity ◽  
Renin Release ◽  
Soluble Form ◽  
Freezing And Thawing ◽  
External Concentration ◽  
Osmotic Lysis ◽  
Membrane Bound ◽  
Release Form ◽  
Three Components

1. Renin release from isolated dog renin granules was limited to within 20% of the total renin during incubation at 37°C in isotonic medium and did not depend on the external concentration of renin. 2. Although the renin granules were osmotically and mechanically fragile, they were quite stable at 0°C in isotonic medium. 3. The bulk of renin activity appeared in the supernatant when the granules were ruptured by osmotic lysis. About 8% of the total renin still remained in the membrane fraction of the granules after treatment by freezing and thawing. 4. Therefore stored renin in the granules can be described as comprising three components: a readily released soluble form; a soluble but hard-to-release form; a membrane-bound form.

scholarly journals Biosynthesis of intestinal microvillar proteins. Pulse-chase labelling studies on maltase-glucoamylase, aminopeptidase A and dipeptidyl peptidase IV

1983 ◽  
Vol 210 (2) ◽  
pp. 389-393 ◽  
Author(s):  
E M Danielsen ◽  
H Sjöström ◽  
O Norén
Keyword(s):  
Organ Culture ◽  
Membrane Fraction ◽  
Bound State ◽  
Dipeptidyl Peptidase ◽  
Dipeptidyl Peptidase Iv ◽  
Soluble Form ◽  
Membrane Bound ◽  
Aminopeptidase A ◽  
High Mannose ◽  
Small Intestinal

The biogenesis of three intestinal microvillar enzymes, maltase-glucoamylase (EC 3.2.1.20), aminopeptidase A (aspartate aminopeptidase, EC 3.4.11.7) and dipeptidyl peptidase IV (EC 3.4.14.5), was studied by pulse-chase labelling of pig small-intestinal explants kept in organ culture. The earliest detectable forms of the enzymes were polypeptides of Mr 225000, 140000 and 115000 respectively. These were found to represent the enzymes in a ‘high-mannose’ state of glycosylation, as judged by their susceptibility to treatment with endo-beta-N-acetylglucosaminidase H (EC 3.2.1.96). After about 40-60 min of chase, maltase-glucoamylase, aminopeptidase A and dipeptidyl peptidase IV were further modified to yield the mature polypeptides of Mr 245000, 170000 and 137000 respectively, which were expressed at the microvillar membrane after 60-90 min of chase. The fact that the enzymes before reaching the microvillar membrane were found in a Ca2+-precipitated membrane fraction (intracellular and basolateral membranes), but not in soluble form, indicates that during biogenesis maltase-glucoamylase, aminopeptidase A and dipeptidyl peptidase IV are transported and assembled in a membrane-bound state.

Tissue Cholinesterases. A Comparative Study of Their Kinetic Properties

2000 ◽  
Vol 55 (1-2) ◽  
pp. 100-108 ◽  
Author(s):  
Kunjan R. Dave ◽  
Anshu R. Syal ◽  
Surendra S. Katyare
Keyword(s):  
Human Serum ◽  
Erythrocyte Membranes ◽  
Soluble Form ◽  
Kinetic Properties ◽  
Rat Serum ◽  
Human Erythrocyte Membranes ◽  
Substrate Saturation ◽  
Membrane Bound ◽  
The One ◽  
Three Components

Abstract The substrate saturation and temperature-dependent kinetic properties of soluble and membrane-bound forms of acetylcholinestarase (AChE) from brain and butyrylcholinesterase (BChE) from heart and liver were examined. In simultaneous studies these parameters were also measured for AChE in erythrocyte membranes and for BChE in the serum from rat and humans. For both soluble and membrane-bound forms of the enzyme from the three tissues, two components were discernible. In the brain, Km of component I (high affinity) and component II (low affinity) was somewhat higher in membrane-bound form than that of the soluble form components, while the Vmax values were significantly higher by about five fold. In the heart, K m of component II was lower in membrane-bound form than in the soluble form, while Vmax for both the components was about four to six fold higher in the membrane-bound form. In the liver, Vmax was marginally higher for the two components of the membrane-bound enzyme; the Km only of component I was higher by a factor of 2. In the rat erythrocyte membranes three components of AChE were present showing increasing values of Km and Vmax. In contrast, in the human erythrocyte membranes only two components could be detected; the one corresponding to component II of rat erythrocyte membranes was absent. In the rat serum two components of BChE were present while the human serum was found to possess three components. Component I of the human serum was missing in the rat serum. Temperature kinetics studies revealed that the Arrhenius plots were biphasic for most of the systems except for human serum. Membrane binding of the enzyme resulted in decreased energy of activation with shift in phase transition temperature (Tt) to near physiological temperature.

scholarly journals Purification of Membrane-Bound Glycoprotein

1977 ◽  
Author(s):  
I.M. Hasitz ◽  
T. Okumura ◽  
G.A. Jamieson
Keyword(s):  
Platelet Aggregation ◽  
Sodium Chloride ◽  
Membrane Fraction ◽  
Plasma Membranes ◽  
Soluble Form ◽  
Binding Ability ◽  
One Dimensional ◽  
Glycoprotein I ◽  
Membrane Bound ◽  
Sds Electrophoresis

Glycocalicin (Mr 150,000) is a component of the platelet glycocalyx and is released in soluble form on platelet homogenization. Glycocalicin appears to play a central role in platelet aggregation induced by thrombin and ristocetin. In addition, the membrane fraction can be resolved into four glycoprotein bands by one-dimensional gel SDS electrophoresis (Mr 150,000, 120,000, 100,000, and 85,000). Since glycoprotein I and glycocalicin are similar electrophoretically and in the nature of their macroglycopeptides, we have endavored to solubilize and characterize membrane-bound glycoprotein I. Extraction of isolated platelet plasma membranes with 1 M sodium chloride or other salts (KBr, KI, KCNS) consistently solubilized 40-60% of glycoprotein I together with thrombosthenin and other components. Homogeneous glycoprotein I was obtained following chromatography on hydroxylapatite. Glycoprotein I purified in this way and glycocalicin, itself, had identical thrombin-binding ability as measured by the Majerus technique. These results suggest that the two types of molecule are funtionally identical but that the molecule can present itself in the platelet in-three different forms — glycocalicin, saline-soluble glycoprotein I and detergent soluble glycoprotein I.

Abstract 158: Role of Prorenin Receptor in the Enhancement of Renin Activity in the Urine of Diabetic Patients

Hypertension ◽  
2013 ◽  
Vol 62 (suppl_1) ◽  
Author(s):  
Danielle Y Arita ◽  
Christina Luffman ◽  
Camille T Bourgeois ◽  
Tina Thethi ◽  
Gabrielle Dawkins ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Diabetic Nephropathy ◽  
Low Ph ◽  
Renin Activity ◽  
Soluble Form ◽  
Urine Ph ◽  
Prorenin Receptor ◽  
Membrane Bound ◽  
Urine Levels

High prorenin levels in the circulation are associated with the progression of diabetic nephropathy and microvascular changes in diabetes. In spite of high plasma prorenin, the urine of diabetes mellitus patients exhibits very low pH and contains high levels of “active” renin, but low levels of prorenin. Prorenin binding to the prorenin receptor (PRR) results in non-proteolytic activation of prorenin and stimulation of intracellular synthesis of transforming growth factor-beta (TGF-β). Furthermore, the PRR cytosolic domain is associated with the vacuolar H+-ATPase, which is involved in acid-base homeostasis by renal intercalated cells. In diabetes, the collecting duct is the major source of prorenin and PRR is upregulated in the kidneys of diabetic rats. We examined the relationships among urine levels of renin (uRen), prorenin (uPro), soluble PRR (sPRR) and TGF-β (uTGF-β) in 93 subjects, including non-diabetes mellitus (Non-DM: n=64); and type-2 diabetes mellitus (DM; n=29) patients. Urine albumin (uAlb), creatinine (uCr) and pH were also assessed. DM patients showed higher uRen levels (DM: 81±21 vs Non-DM: 29±4.5 ng AngI/mL/hr; p<0.001), which were positively associated with uAlb/uCr (p<0.05, r=0.21) and inversely correlated with urine pH (p<0.01, r=-0.38). These values contrasted with uPro levels, which were no different between groups. DM patients showed increased uTGF-β compared to Non-DM (DM: 22±5.3 vs Non-DM: 5.6±1.5 pg/mg uCr; p<0.0001). Urine sPRR levels were positively correlated with urine pH (p<0.0001, r=0.56). No differences were observed in sPRR plasma and urine levels between non-DM and DM patients. However, the plasma levels of sPRR were 12.5 and 18.5-fold higher than in urine of Non-DM and DM, respectively. Treatment with RAS blockers increased sPRR in plasma (DM with RAS blockade: 24,455±2,151 vs DM without RAS blockade: 17,726±1,255 pg/mL, p<0.001) but not in urine. These data suggest that the cell membrane-bound PRR, not the soluble form, might be responsible for the increases in renin activity and TGF-β, as well as in the low pH in the urine of type-2 DM patients. It is likely that prorenin-mediated activation of membrane bound PRR promotes diabetic nephropathy by increasing urinary formation of TGF-β.

Enhancement of the Antihypertensive Effect of Hydrochlorothiazide in Dogs after Suppression of Renin Release by Beta-Adrenergic Blockade

1975 ◽  
Vol 48 (2) ◽  
pp. 147-151
Author(s):  
C. S. Sweet ◽  
M. Mandradjieff
Keyword(s):  
Blood Pressure ◽  
Plasma Renin Activity ◽  
Arterial Blood Pressure ◽  
Antihypertensive Effect ◽  
Plasma Renin ◽  
Renin Activity ◽  
Renin Release ◽  
Antihypertensive Activity ◽  
Adrenergic Blockade ◽  
Arterial Blood

1. Renal hypertensive dogs were treated with hydrochlorothiazide (8−2 μmol/kg or 33 μmol/kg daily for 7 days), or timolol (4.6 μmol/kg daily for 4 days), a potent β-adrenergic blocking agent, or combinations of these drugs). Changes in mean arterial blood pressure and plasma renin activity were measured over the treatment period. 2. Neither drug significantly lowered arterial blood pressure when administered alone. Plasma renin activity, which did not change during treatment with timolol, was substantially elevated during treatment with hydrochlorothiazide. 3. When timolol was administered concomitantly with hydrochlorothiazide, plasma renin activity was suppressed and blood pressure was significantly lowered. 4. These observations suggest that compensatory activation of the renin-angiotensin system limits the antihypertensive activity of hydrochlorothiazide in renal hypertensive dogs and suppression of diuretic-induced renin release by timolol unmasks the antihypertensive effect of the diuretic.

scholarly journals Contamination of free-ribosome fractions by detached previously membrane-bound ribosomes (Short Communication)

1974 ◽  
Vol 138 (2) ◽  
pp. 305-307 ◽  
Author(s):  
K. O'Toole
Keyword(s):  
Rat Liver ◽  
Membrane Fraction ◽  
Short Communication ◽  
Free Ribosome ◽  
Membrane Bound ◽  
Free Polyribosome

A rough-membrane fraction isolated from rat liver by a procedure designed to prevent membrane denaturation was subjected to the gradient treatment normally used to isolate free ribosomes. Under these conditions, at most 20% of the ribosomes were detached from membrane with less than 5% sedimenting into the free-polyribosome pellet.

Soluble neutral maltase–glucoamylase from the small intestine: separation and characterization of components with differing affinity for concanavalin A

1982 ◽  
Vol 60 (11) ◽  
pp. 1007-1013 ◽  
Author(s):  
G. Forstner ◽  
A. Salvatore ◽  
L. Lee ◽  
J. Forstner
Keyword(s):  
Concanavalin A ◽  
Gradient Elution ◽  
Soluble Form ◽  
Rat Intestine ◽  
Ph Optimum ◽  
Molecular Weights ◽  
Neutral Ph ◽  
Membrane Bound ◽  
Sepharose 4B

Intestinal maltase with a neutral pH optimum exists in both a brush border membrane-bound form and a soluble form in suckling rat intestine. Previous experiments in our laboratory have shown that the soluble enzyme contains a component which binds much more tightly to concanavalin A (ConA) than solubilized forms of the membrane enzyme. We studied the origin of this component by subjecting neutral, soluble maltase activity to chromatography on Sepharose 4B at age 13, 18 (preweaning), and 25 (postweaning) days. At 13 days, two maltase peaks were obtained with approximate molecular weights of 400 000 (peak I) and 150 000 (peak II). Peak II was less prominent at 18 days and was absent at 25 days. At 13 days, the majority of peak I consisted of material which was bound between 0.025 and 0.05 M α-methyl mannoside on gradient elution chromatography of ConA-Sepharose. Peak II contained material which eluted between 0.075 and 0.3 M α-methyl mannoside. At 25 days, all of the soluble maltase eluted between 0.025 and 0.04 M α-methyl mannoside. Peak I and peak II maltases had similar pH optima and Km's for maltase. Peak II maltase had a fourfold greater activity toward glycogen than peak I maltase with approximately the same activity for palatinose, turanose, and trehalose. Both maltases were precipitated by an antibody raised against adult membrane-bound maltase. Soluble maltase with neutral pH activity in the suckling rat intestine, therefore, consists of two immunologically related isozymes which differ in their molecular weight, their binding by ConA, and their specificity for glycogen. The small isozyme disappears at or about the time of weaning.

Suppression of renin release by antagonism of endogenous opiates in the dog

1986 ◽  
Vol 250 (4) ◽  
pp. R633-R637
Author(s):  
J. E. Szilagyi ◽  
J. Chelly ◽  
M. F. Doursout
Keyword(s):  
Plasma Renin Activity ◽  
Plasma Renin ◽  
Endogenous Opioids ◽  
Renin Activity ◽  
Renin Release ◽  
Endogenous Opioid ◽  
Endogenous Opiates ◽  
Arterial Blood ◽  
Before And After ◽  
Arterial Constriction

The influence of blockade of endogenous opioids on the release of renin due to partial renal arterial constriction was determined acutely and chronically in unilaterally nephrectomized dogs. In acute preparations changes in plasma renin activity, arterial blood pressure, and heart rate were determined after 15 min of 60% renal arterial constriction before and after administration of either a saline vehicle, the opiate antagonist naloxone (0.05 mg/kg), or morphine (2 mg/kg). Acute antagonism of endogenous opiates abolished the increase in plasma renin activity and mean arterial pressure associated with renal arterial constriction. Repeated renal arterial constrictions in saline- or morphine-treated animals did not alter the humoral or hemodynamic responses. In chronic preparations long-term naloxone infusion attenuated the development of renovascular hypertension and diminished the increase in plasma renin activity. These data suggest that endogenous opioid peptides are modulators in the control of renin release and may be important participants in the pathogenesis of hypertension.

scholarly journals Characterization of the soluble, secreted form of urinary meprin

1996 ◽  
Vol 315 (2) ◽  
pp. 461-465 ◽  
Author(s):  
Robert J. BEYNON ◽  
Simon OLIVER ◽  
Duncan H. L. ROBERTSON
Keyword(s):  
Proteolytic Activity ◽  
Protein Band ◽  
Peptide Sequence ◽  
Soluble Form ◽  
Α Subunit ◽  
Alternative Processing ◽  
Sds Page ◽  
Processing Pathways ◽  
Membrane Bound

A soluble form of the kidney membrane metalloendopeptidase, meprin, is present in urine. Urinary meprin is expressed in BALB/C mice with the Mep-1a/a genotype (high meprin, expressing meprin-α and meprin-β) but not in BALB.K mice of the Mep-1b/b genotype (that only express meprin-β). Western blotting with antisera specific to the meprin-α and the meprin-β subunits established that the only form of meprin present in urine samples was derived from meprin-α. This form of meprin is partially active, and comprises at least three variants by non-reducing SDS/PAGE and by zymography and two protein bands on reducing SDS/PAGE. Sequencing of these two bands established that the N-terminus of the larger protein band begins with the pro-peptide sequence of the α-subunit (VSIKH..), whereas the smaller band possessed the mature meprin N-terminal sequence (NAMRDP..). Trypsin is able to remove the pro-peptide, with a concomitant activation in proteolytic activity. After deglycosylation, the size of the pro- and mature forms of urinary meprin are consistent with cleavage in the region of the X–I boundary. There is a pronounced sexual dimorphism in urinary meprin expression. Females secrete a slightly larger form, and its proteolytic activity is about 50% of that released by males. The urinary meprin is therefore a naturally occurring secreted form of this membrane-bound metalloendopeptidase and is more likely to be generated by alternative processing pathways than by specific release mechanisms.

scholarly journals Role of glycosylation in transport and enzymic activity of neutral endopeptidase-24.11

1994 ◽  
Vol 302 (2) ◽  
pp. 451-454 ◽  
Author(s):  
M H Lafrance ◽  
C Vézina ◽  
Q Wang ◽  
G Boileau ◽  
P Crine ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Cell Surface ◽  
Intracellular Transport ◽  
Neutral Endopeptidase ◽  
Soluble Form ◽  
Cell Extracts ◽  
Glycosylation Sites ◽  
Sugar Addition ◽  
Membrane Bound

Neutral endopeptidase (NEP, EC 3.4.24.11) is a major ectoenzyme of the brush-border membrane. The ectodomain of NEP contains five putative N-glycosylation sites. In order to determine the role of the addition of sugar moieties on the activity and intracellular transport of NEP, we have used site-directed mutagenesis to remove all or some of the five potential sites of sugar addition in membrane-bound and secreted forms of the enzyme. Expression of NEP glycosylation mutants in COS-1 cells showed that all five sites are used for sugar addition. Immunoblotting of NEP in COS-1 cell extracts or culture media indicated that total expression of normal membrane-bound NEP was not affected by mutations at glycosylation sites, whereas this expression level appeared to be strictly dependent on the number of glycosylation sites retained on the soluble form. The transport to the cell surface was also reduced by decreased glycosylation, but again the phenomenon appeared more drastic in the case of the soluble form than for the membrane-bound enzyme. Enzyme activity was decreased by deglycosylation. However, the presence of either of two crucial sites (sites 1 and 5; numbered from the N-terminus of the protein) was sufficient to recover close-to-normal enzymic activities. Transport to the cell surface and enzyme activity of NEP are thus both dependent on sugar residues, probably through different conformational constraints. These constraints seem to be local for enzyme activity but more global for transport to the cell surface.

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