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PubMed1995

A novel proline, glycine: K+ symporter in midgut brush-border membrane vesicles from larval Manduca sexta.

Alkali-cation-dependent uptake of proline and glycine into brush-border membrane vesicles from the midgut of the larval tobacco hornworm Manduca sexta was investigated using rapid filtration assays. Uptake of both amino acids was by electrophoretic symport, with K+ being the favored cation at pH 10. Counterflow accumulation of proline was elicited by glycine and vice versa, suggesting that the two amino acids are transported by a common symporter, which we designate the pro, gly: K+ symporter. L-alpha-Aminoisobutyric acid was the only other amino acid that elicited the accumulation of both proline and glycine. D-Proline was not symported; L-proline, glycine and L-alpha-aminoisobutyric acid appear to be the only substrates of the pro, gly: K+ symporter. Neutral amino acids with relatively short sidechains elicit glycine accumulation, suggesting that glycine may also be symported by the well-established neutral amino acid system. Since proline does not utilize the broad-spectrum, neutral system, its symport appears to be exclusively through the pro, gly: K+ symporter. Proline symport was found mainly in posterior midgut vesicles, suggesting that the pro, gly: K+ symporter may be localized in this region of the midgut.

Animals↗
PubMed2005

Effect of proline and K+ on the stimulation of cellular activities in Escherichia coli K-12 under high salinity.

Growth of Escherichia coli K-12 in a modified Davis minimal medium was inhibited under high osmolarity, but it recovered remarkably with the addition of 1 mM proline. The co-existence of K+ with proline enhanced the recovery of growth under high osmolarity more than that in the presence of proline alone. The same was true for the activities of respiration and glucose uptake. A similar supplementary effect of K+ was observed for the activities of proline uptake under high osmolarity. These results suggest that K+ and proline support not only growth but respiration and uptake of the respiratory substrate glucose in the cell cytoplasm when exposed to high osmolarity. External K+ almost disappeared with 1 h of incubation at low osmolarity, indicating that active accumulation of K+ in the cells occurred. On the other hand, a gradual accumulation of K+ was recognized at high osmolarity in the presence of 1 M NaCl, especially at > 2 h of incubation. This study of L-[5-3H]proline uptake in the cell cytoplasm indicates that proline was incorporated as a substrate of protein synthesis in the absence of NaCl, but was efficiently utilized as a compatible solute in the presence of high concentrations of NaCl.

Cations, Monovalent↗
PubMed1991

Chloride and membrane potential dependence of sodium ion-proline symport.

Proline accumulation by renal proximal tubule brush border membrane vesicles is Na+ dependent, but little is known about the role of anions or membrane potential on proline uptake. Recent studies in a variety of transport systems, including rat renal brush border membrane vesicles, indicate that halide anions chloride (Cl-) and bromide (Br-) are essential for glycine, beta-alanine, gamma-aminobutyric acid, and taurine uptake, so the possibility that Na(+)-proline symport is Cl- dependent was explored. Also, the role of membrane potential on transport was assessed by determining the effect of external anions with different membrane permeabilities. The ratio of initial rate Cl- stimulated to thiocyanate (SCN)(-)-stimulated uptake values serves to measure Cl- dependence. The initial rate of proline uptake to equilibrium value was 3.11 +/- 0.5 (SE) in the presence of Cl- versus SCN-. The ratio for D-glucose, whose uptake is governed only by electrogenic status of the membrane, was 0.61 +/- 0.47 (P less than 0.001 versus proline). In another series of experiments, uptake values for various anions as a percent of equilibrium (I/E x 100) were: SCN-, 84.9 +/- 10.9; NO3, 49.9 +/- 11.0; SO4(2-), 27.3 +/- 4.4; F-, 68.5 +/- 18.3; Cl-, 164.1 +/- 44.6; Br-, 150.6 +/- 30.2; I-, 56.7 +/- 13.5. The stoichiometry of uptake by Hill plot analysis of proline uptake in the presence of varying concentrations of Na+ (0 to 100 mM) and Cl- (0 to 100 mM) was 2Na+:1Cl-:1 proline.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Transport Systems, Neutral↗
PubMed1995

Regional hemodynamic changes and vasopressin release induced by intracisternal injection of L-proline in the conscious rat.

Electromagnetic flow probes were used to measure regional blood flow responses to central injection of L-proline in conscious rats. Ten min after intracisternal injection of 10 mumol of L-proline, arterial pressure increased from 113 +/- 1.6 (mean +/- SEM, n = 23) to 142 +/- 2.9 mmHg, while the heart rate decreased from 383 +/- 9.6 (n = 23) to 313 +/- 5.4 beats/min, vascular resistance increased an average of 239% in the superior mesenteric artery (n = 8) and 72% in the renal artery (n = 8), without change in the terminal aorta (-6%, n = 7). However, 10 mumol of D-proline induced neither blood pressure increase nor bradycardia 10 min after its injection. After sino-aortic denervation, the heart rate was not decreased by L-proline injection. Ganglionic blockade with chlorisondamine evoked significantly greater pressor action by L-proline injection than that without treatment, but intravenous injection of the vasopressin antagonist, (d(CH2)5(1), O-Me-Tyr2, Arg8)-vasopressin (10 micrograms/kg), promptly dilated the superior mesenteric vascular bed and lowered the arterial pressure. In addition, pretreatment with the vasopressin antagonist alone almost abolished the pressor and vasoconstrictor action induced by L-proline injection. These results indicate that intracisternal injection of L-proline specifically elicited an increase in arterial pressure mainly through marked vasoconstriction of the superior mesenteric artery bed, and that bradycardia was elicited via the baroreflex. Thus, vasopressin release in the blood-stream was involved in these hemodynamic actions.

Animals↗
PubMed1996

Localization of proline-like immunoreactivity in young rat retinal neurons.

PURPOSE: To localize proline in the rat retina. METHOD: We prepared antibodies raised against proline coupled to bovine serum albumin (BSA) with glutaraldehyde. To confirm the specificity of the antiserum, crossreactivity with other amino acids was determined using an immunodot procedure. Rat eyes were enucleated on postnatal day 21. Immunohistochemistry was performed on semi-thin sections using gold-labelled secondary antibodies and a silver-enhancement technique. RESULTS: Immunodots revealed that the antiserum was specific for proline. Amino acids from retinal extracts were separated on gel, transferred to BSA-glutaraldehyde treated filters, and stained with antibodies to determine if our antibody reacted only with proline. Staining was most intense on postnatal day 21 and disappeared in the adult retina. In addition to Muller cells, horizontal cells, amacrine cells, and some cells in the ganglion cell layer were labelled. CONCLUSIONS: Antibodies raised against proline revealed a transient immunoreactivity in young rat neurons. Our findings strongly indicate that the retina may express a high level of proline in the developmental stages. This result may provide a clue for clarifying the role of proline in the retina.

Animals↗
PubMed1990

Synthesis and inhibitory activity of acyl-peptidyl-prolinalderivatives toward post-proline cleaving enzyme as nootropic agents.

Several prolinal derivatives were synthesized and examined for their inhibitory activity on post-proline cleaving enzymes from Flavobacterium meningosepticum and bovine brain and their possible properties as nootropic agents. Almost all the compounds tested inhibited the activity of both enzymes at low IC50 values of the order of nM, but a specificity difference was observed with alkylacyl-prolinal derivatives which strongly inhibited only the bacterial enzyme. Prolyl-prolinal derivatives were the most effective inhibitors for both enzymes. In the passive avoidance test using amnesic rats experimentally induced with scopolamine, the prolinal derivatives that have potent inhibitory activity toward post-proline cleaving enzymes showed also strong anti-amnesic activities at dose of 10-1000 micrograms/kg, i.p. Some of the compounds showed a bell-shape dose dependency. These results suggest that the post-proline cleaving enzymes play an important role in the regulation of learning and memory consolidation in the brain and inhibitors of these enzymes are suggested as possible candidates for nootropic agents, particularly for an anti-amnesic drug.

Amino Acid Sequence↗
PubMed1975

Transport of sugars and amino acids in bacteria. XIII. Mechanism of selective inhibition of the active transport reactions for proline, leucine, and succinate by zinc ions.

A mutant (S-1) of Escherichia coli which lacks succinate dehydrogenase [EC 1.3.99.1] but has normally succinate transport system, and various oxidase activities other than succinate, was isolated from the strain U24. Using these strains studies were made on the effects of zinc ions on the active transport reactions for succinate proline, and leucine. Zinc ions inhibited succinate transport reaction and succinate oxidation by intact cells. The active transport reaction for proline, which was supported by endogenous energy source in intact cells, was slightly inhibited by zinc ions. This inhibition was not reversed by large excess of magnesium ions. The initial rates of active uptakes of proline were increased by exogenous energy sources such as succinate and glycerol and zinc ions greatly inhibited these. However, D-lactate dependent proline uptake was enhanced slightly by the presence of zinc ions. It was found that zinc ions at a high concentration enhanced the steady level of proline accumulation in cells. This mechanism was studied in detail and we concluded that zinc ions inhibited completely the exchange-exit reaction for proline. Effects of zinc ions on the active transport reaction for leucine were rather simple when compared with these for proline. Zinc ions inhibited strongly the initial rates of leucine uptakes which were driven by endogenous and exogenous energy sources. The ions also inhibited the exchange-exit reaction.

Biological Transport, Active↗
PubMed2000

[Effect of mutations in PHO85 and PHO4 genes on utilization of proline in Saccharomyces cerevisiae yeasts].

Yeast Saccharomyces cerevisiae can utilize proline as a single nitrogen source. We have found that the strains with mutations in gene PH085, a structural gene encoding cyclin-dependent phosphoprotein kinase, cannot grow on the proline-containing media. The ability to utilize proline is restored in strains of the pho85pho4 genotype. We suggest that phosphoprotein kinase Pho85p is involved in either phosphorylation of a highly specific proline permease, Put4p, or in signaling proline concentration. The Pho4p protein that activates transcription of the PH05 gene, a structural gene of acid phosphatase, seems to participate in the negative regulation of the PUT1 and PUT2 genes encoding enzymes of proline catabolism, proline oxidase and delta-pyrroline-5-carboxylate dehydrogenase. Thus, regulation of phosphorus and nitrogen metabolism have common elements.

Acid Phosphatase↗
PubMed1988

Purification and reconstitution of Escherichia coli proline carrier using a site specifically cleavable fusion protein.

We previously constructed a bifunctionally active membrane-bound fusion protein, in which Escherichia coli proline carrier (the product of the putP gene) was linked with beta-galactosidase (the product of the lacZ gene) through a collagen linker (Hanada, K., Yamato, I., and Anraku, Y. (1987) J. Biol. Chem. 262, 14100-14104). The proline carrier was purified from this site specifically cleavable fusion protein. Cytoplasmic membranes overproducing the fusion protein were solubilized with dodecylmaltoside, and the solubilized fraction was subjected to anti-beta-galactosidase IgG-Sepharose chromatography. The fusion protein was specifically adsorbed to the immunoaffinity resin and then treated with collagenase for splitting the proline carrier moiety of the fusion protein from the beta-galactosidase moiety. The collagenase used for the collagenolysis was then removed by anti-collagenase IgG-Sepharose chromatography. In this way, the proline carrier was purified to more than 95% homogeneity of the protein. Proline transport in proteoliposomes reconstituted with the purified carrier was dependent on the membrane potential and the chemical gradient of Na+ across the membrane with apparent Michaelis constants for proline and for Na+ stimulation of 3.6 microM and 31 microM, respectively. These results indicated that the proline carrier mediates electrogenic Na+/proline symport.

Amino Acid Transport Systems, Neutral↗
PubMed1979

Fascioliasis: similarities of the anemia in rats to that produced by infused proline.

Fasciola hepatica releases large amounts of proline into the bile of its host. Significant increases in the levels of other amino acids in the bile also occur. The present investigation examines whether proline and these other amino acids may play a role in inducing the anemia that frequently accompanies fascioliasis. In experiments, rats were infused intra-abdominally for 2 weeks with 1 of 3 solutions: 20.0 mM proline in saline, a mixture of 8 amino acids (excluding proline) each at 2.0 mM in saline, or saline only. At the end of the experiments 2 cc of blood was removed from each rat, via cardiac puncture. The heparinized blood was used to count erythrocytes and reticulocytes, and to measure hematocrit and mean corpuscular volume (MCV). Analysis of variance disclosed highly significant differences in erythrocyte counts, MCV, and reticulocyte counts among the 5 groups. A Student-Newman-Keuls test indicated that the Proline and Infected groups were not different from each other (except for MCV, where proline's effect was more severe) and that both groups differed significantly from the Amino Acid group, the Saline group, and the Control group. Hence, it appears that infused proline can cause an anemia similar to that induced by Fasciola.

Amino Acids↗
PubMed1981

Purification of the putA gene product. A bifunctional membrane-bound protein from Salmonella typhimurium responsible for the two-step oxidation of proline to glutamate.

In this paper we report the purification of a protein which is able to catalyze both the proline oxidase and the pyrroline-5-carboxylic acid dehydrogenase activities necessary for the oxidation of proline to glutamic acid. The purification involves the preparation of a crude membrane pellet, detergent solubilization, ammonium sulfate fractionation, and DEAE-chromatography. We are able to obtain an essentially pure preparation (greater than 95% pure) after only a 52-fold purification, demonstrating that the protein is a major protein in cells fully induced for proline utilization. Both proline oxidase and pyrroline-5-carboxylic acid dehydrogenase activities co-purity throughout our purification. Velocity sedimentation of the purified protein demonstrates that both proline oxidase and pyrroline-5-carboxylic acid dehydrogenase activities co-sediment. Early in the purification procedure we are able to detect two species of protein which have both proline oxidase and pyrroline-5-carboxylic acid dehydrogenase activities. Our procedure purifies only the larger molecular weight species. The purified protein is a dimer composed of identical 132,000-dalton subunits. Analysis of mutants defective for proline utilization demonstrate that the bifunctional enzyme is the putA gene product.

1-Pyrroline-5-Carboxylate Dehydrogenase↗
PubMed1983

Can isolated spans of the tricarboxylic acid cycle operate independently? L-proline, oleate and butyrate metabolism in rat hepatocytes.

14CO2 production from [l-14C]oleate, [l-14C]butyrate and [U-14C]proline by isolated rat hepatocytes was studied. In hepatocytes from fed rats, fatty acid and proline oxidation are stimulated in parallel by adrenaline, noradrenaline, vasopressin and angiotensin II. In contrast in hepatocytes from 24 h-starved rats these hormones stimulate proline oxidation whereas oleate and butyrate oxidation is hormone-insensitive. This suggests that 14CO2 production from [U-14C]proline and [l-14C]oleate is subject to independent endocrine control. In support of this in hepatocytes from fed rats, glucagon and dibutyryl cyclic AMP stimulate 14CO2 production from proline but inhibit 14CO2 production from [l-14C]oleate. The pathway of hepatic proline oxidation is discussed and it is suggested that 2-oxoglutarate dehydrogenase is one site of endocrine control of proline oxidation.

Angiotensin II↗
PubMed1994

A new proline-rich protein precursor expressed in the salivary glands of the rat is encoded by a gene homologous to the gene coding for the prohormone-like protein SMR1.

A gene encoding a prohormone-like protein (SMR1) has previously been characterized and shown to be expressed in the rat submandibular glands under androgenic control (Rosinski-Chupin, I., Tronik, D., and Rougeon, F. (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 8553-8557). This gene, now named VCS-alpha 1, belongs to a multigene family (Rosinski-Chupin, I., and Rougeon, F. (1990) DNA Cell Biol. 9, 553-559). We now describe the structure and the expression of a second member (VCS-beta 1) of this family. The two genes differ principally in the protein-coding region, therefore we have named these related genes VCS (variable coding sequence). Genomic clones containing the VCS-beta 1 gene were obtained by screening a lambda EMBL3 library with a probe corresponding to the VCS-alpha 1 cDNA. The nucleotide sequence of VCS-beta 1 predicted a structure containing three exons. This structure, confirmed by sequencing a VCS-beta 1 cDNA obtained by reverse polymerase chain reaction, is identical to the organization of the VCS-alpha 1 gene. Comparison of the VCS-beta 1 and VCS-alpha 1 genomic sequences indicates regions of homology which are unevenly distributed, suggesting a differential evolution of some areas (particularly the third exon) of the VCS genes. The VCS-beta 1 cDNA codes for a proline-rich protein precursor named PR-V beta 1 (148 amino acids, 39.2% proline, 10.8% glycine) and characterized by a secretory signal-peptide and three repeats of a unit rich in proline residues surrounded by two clusters of potential endoprotease cleavage sites. mrNA coding for PR-V beta 1 was detected in the submandibular-sublingual gland complex of male and female rats. PR-V beta 1 is homologous to the proline-rich peptide B isolated from human saliva (Isemura, S., Saitoh, E., and Sanada, K. (1979) J. Biochem. (Tokyo) 86, 79-86) and to the submandibular proline-rich protein precursor MSG1 of the mouse (D. Tronik-Le Roux, M. Senorale-Pose, and F. Rougeon, manuscript in preparation). Our observations provide evidence that in addition to the known proline-rich protein genes, there is, in rodent and probably human genomes, another class of genes coding for salivary proline-rich proteins. The high conservation of various sites for bacterial collagenases localized in the repeat region of PR-V beta 1, MSG1, and PRP-B suggest a protective function of these proteins in the oral cavity.

Amino Acid Sequence↗
PubMedDate not supplied

L-proline loading for the assessment of pituitary GH reserve.

Intravenous insulin (0.1 U/kg body weight) and oral 1-proline (100 mg/kg body weight) tolerance tests were performed in 22 healthy and 30 short-statured children and adolescents and blood glucose, serum immunoreactive growth hormone (GH), immunoreactive insulin (IRI) and 1-proline were determined. The peak level of serum GH was significantly higher following insulin than after 1-proline. The proline loading correctly identified the normality of GH axis in 12 out of 22 controls and in 3 out of 7 normopituitary short-statured patients. The serum 1-proline levels consideration did not improve much the ability of 1-proline load to detect either the normal GH responsiveness or the pituitary insufficiency. The mechanism of GH stimulatory properties of 1-proline in some healthy subjects is not known.

Blood Glucose↗
PubMed1995

A major human lacrimal gland mRNA encodes a new proline-rich protein family member.

PURPOSE: To examine the existence of novel protein products of the human lacrimal gland. METHODS: cDNA clones corresponding to a highly abundant human lacrimal gland mRNA were isolated and sequenced. Tissue distribution of expression was studied by Northern blot analysis, RNase protection analysis, and in situ hybridization. RESULTS: A highly abundant 600-base mRNA was identified, and corresponding cDNA clones were isolated. The mRNA has a 134-residue open reading frame encoding a secreted protein of 13458 Da. This protein shows 45.5% similarity to human salivary acidic proline-rich protein PRP 1 and has a similar domain structure, but, unlike other members of the proline-rich protein family, it lacks a conserved repetitive domain. The lacrimal proline-rich protein is encoded by a single gene, designated as LPRP. Expression of LPRP was also detected in the human submandibular, von Ebners, sublingual, and parotid glands. LPRP was expressed in the acinar cells of the lacrimal gland, and in the submandibular gland expression of the LPRP and PRP 1 genes was localized to the serous acini and demilunes. CONCLUSIONS: The human lacrimal gland produces a previously unknown member of the proline-rich protein family. By analogy with other proline-rich proteins, this LPRP most likely mediates protective functions in the eye, such as modulation of the microflora. In contrast to other proline-rich protein genes, LPRP is expressed in the lacrimal acinar cells, and other anterior exocrine glands. LPRP should be a useful marker for human lacrimal gland acinar cell function in vitro.

Adult↗
PubMed1977

Glucocorticoid control of hepatic proline oxidase.

Since adrenal corticosteroids are known to affect amino acid metabolism and gluconeogenesis, we examined the relationship of these hormones to hepatic proline oxidase, the mitochondrial enzyme degrading L-proline. In adrenalectomized rats hepatic proline oxidase activity decreased to about 50% of control levels within 5-6 days. This depressed activity can be restored to normal by 4 days of corticosteroid repletion. Treatment of intact rats with supraphysiologic doses of corticosteroid further elevated proline oxidase activity. The level in treated intact rats was three-fold that of adrenalectomized rats. Kinetic analysis revealed that corticosteroid increased the amount of enzyme without altering enzyme affinity for proline. Administration of a single dose of corticosteroid to either adrenalectomized or intact animals increased enzyme activities, with a lag time of less than 2 hr. The maximum effect occurred 5-6 hr following injection. Since proline degraded by this pathway can contribute carbon skeletons directly to carbohydrate, corticosteroid induction of proline oxidase may play an important role in hepatic gluconeogenesis occurring with corticosteroid action.

Adrenalectomy↗
PubMed2005

Tumor necrosis factor-alpha mediates pancreatitis responses in acinar cells via protein kinase C and proline-rich tyrosine kinase 2.

BACKGROUND & AIMS: Although tumor necrosis factor alpha is implicated as an important mediator of the inflammatory response in acute pancreatitis, its role in other pathologic features of the disease remains unknown. We investigated the role for tumor necrosis factor alpha in cytoskeletal responses and the underlying signaling mechanisms in pancreatic acinar cells. METHODS: In isolated rat pancreatic acini and AR42J cells, we determined the effect of tumor necrosis factor alpha on the actin cytoskeleton by rhodamine-phalloidin. Using pharmacological and molecular approaches, we assessed the involvement of protein kinase C, Src kinases, and proline-rich tyrosine kinase 2 in the process. We also studied the involvement of these signaling pathways in tumor necrosis factor-alpha-induced nuclear factor-kappaB activation and apoptosis. RESULTS: Tumor necrosis factor-alpha increased the tyrosine phosphorylation of proline-rich tyrosine kinase 2 in acinar cells. The broad-spectrum protein kinase C inhibitor and the Src kinase inhibitor both inhibited tumor necrosis factor-alpha-induced proline-rich tyrosine kinase 2 phosphorylation, but at different tyrosine residues. Using protein kinase C isoform-specific inhibitors and the antisense approach, we showed that protein kinase C delta and mediate proline-rich tyrosine kinase 2 tyrosine phosphorylation. Tumor necrosis factor-alpha caused disorganization of the actin cytoskeleton by a mechanism dependent on protein kinase C, Src kinases, and proline-rich tyrosine kinase 2. Inhibition of protein kinase C, but not Src kinases, decreased tumor necrosis factor-alpha-induced apoptosis. Furthermore, with antisense transfections, we showed that protein kinase C delta and , but not proline-rich tyrosine kinase 2, mediate tumor necrosis factor alpha-induced nuclear factor-kappaB activation. CONCLUSIONS: Tumor necrosis factor-alpha activates proline-rich tyrosine kinase 2 to cause cytoskeletal disorganization and nuclear factor-kappaB to cause inflammatory response, and it triggers cell death signaling through divergent mechanisms mediated by protein kinase C. The results provide insights into the mechanisms in pancreatic acinar cells that link tumor necrosis factor alpha to critical processes in acute pancreatitis.

Acute Disease↗
PubMed1997

Isolation and characterization of two mutants of human profilin I that do not bind poly(L-proline).

A simple procedure for the isolation of profilin mutants having a reduced capacity to bind poly(L-proline) is used to isolate two mutants of human profilin I, W3N and H133S. Binding of the mutants to poly(L-proline), actin, and phosphatidylinositol (4,5)-bisphosphate (PIP2) was studied. Both mutations abolished the poly(L-proline)-binding activity of profilin. This suggests that the arrangement of the N- and C-terminal helices forming the poly(L-proline)-binding site depends on the stabilizing interaction between W3 and W31 in the underlying beta-strand, and that the H133S mutation in the C-terminal helix also must have distorted the arrangement of the terminal helices. Both mutations caused a reduced affinity for actin, with the W3N replacement having the most pronounced effect. This shows that structural changes in the poly(L-proline)-binding region of profilin can affect the distantly located actin-binding site. Thus, ligands influencing the structure of the poly(L-proline)-binding site may regulate actin polymerization through profilin. This is consonant with the finding that PIP2, which changes the tryptophan fluorescence in wild-type profilin and dissociates the profilin:actin complex in vitro, binds more strongly to the W3N mutant profilin. Thus, the poly(L-proline)-binding surface represents a crucial regulatory site of profilin function.

Contractile Proteins↗