scholarly journals Dipeptide uptake: A novel marker for testicular and ovarian macrophages

1996 ◽  
Vol 245 (4) ◽  
pp. 662-667 ◽  
Author(s):  
Christiane Otto ◽  
Karl Bauer
Keyword(s):  
Dipeptide Uptake

Intestinal glycyl-L-phenylalanine and L-phenylalanine transport in a euryhaline teleost

1991 ◽  
Vol 260 (3) ◽  
pp. R563-R569 ◽  
Author(s):  
S. J. Reshkin ◽  
G. A. Ahearn
Keyword(s):  
Significant Contribution ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Transport Mechanisms ◽  
Intestinal Brush Border Membrane ◽  
Overshoot Phenomenon ◽  
Independent Process ◽  
Euryhaline Teleost ◽  
Dipeptide Uptake ◽  
Phenylalanine Transport

The transport mechanisms for the dipeptide glycyl-L-phenylalanine (Gly-Phe) and L-phenylalanine (Phe) were characterized in fish intestinal brush-border membrane vesicles (BBMV). Gly-Phe was rapidly hydrolyzed only intravesicularly with almost total hydrolysis occurring even at 10 s. Dipeptide uptake was not stimulated by an inward gradient of Na, K, or H. Phe uptake was stimulated by an inward gradient of either Na or K but displayed an overshoot phenomenon only in the presence of an Na gradient. Kinetic analysis of the effect of substrate concentration on transport rate revealed that transport of both Gly-Phe and Phe occurred by a saturable process conforming to Michaelis-Menten kinetics. The Km for Gly-Phe was 9.8 +/- 3.5 mM, whereas that for Phe in the presence of Na or K, respectively, was 0.74 +/- 0.13 and 1.1 +/- 0.37 mM. Maximum uptake for Gly-Phe and for Phe in the presence of Na and K was 5.1, 0.9, and 0.4 nmol.mg and protein-1.5 s-1, respectively. Gly-Phe and Phe transport displayed different patterns of inhibition by dipeptides and amino acids. These results suggest that Gly-Phe and Phe are transported via different mechanisms, with Gly-Phe being hydrolyzed during a carrier-mediated, cation-independent process and Phe being transferred via a Na+ cotransport process similar to that described in mammals. During conditions of high luminal dipeptide concentrations, the Gly-Phe pathway may make a significant contribution to total Phe uptake.

Calu-3 cells grown under AIC and LCC conditions: Implications for dipeptide uptake and transepithelial transport of substances

2011 ◽  
Vol 78 (1) ◽  
pp. 19-26 ◽  
Author(s):  
Anna Stentebjerg-Andersen ◽  
Ingrid Vedsted Notlevsen ◽  
Birger Brodin ◽  
Carsten Uhd Nielsen
Keyword(s):  
Transepithelial Transport ◽  
Dipeptide Uptake

Uptake of l-Leucyl-l-Leucine and Glycylsarcosine by Hamster Jejunum in Vitro

1983 ◽  
Vol 65 (2) ◽  
pp. 177-184 ◽  
Author(s):  
D. M. Matthews ◽  
D. Burston
Keyword(s):  
Amino Acid ◽  
Intestinal Transport ◽  
Inhibitory Effect ◽  
Complete Inhibition ◽  
Maximal Velocity ◽  
Uptake System ◽  
Apparent Affinity ◽  
Kinetics Of Uptake ◽  
Dipeptide Uptake

1. Preliminary observations of the effects on intestinal transport of the lipophilic properties of the amino acid side chains of a series of neutral dipeptides showed that, contrary to expectation, l-valyl-l-valine and not l-leucyl-l-leucine was the most powerful inhibitor of uptake of the hydrolysis-resistant dipeptide glycylsarcosine by hamster jejunum in vitro. 2. Investigation of the kinetic characteristics of uptake of l-leucyl-l-leucine showed that Kt and Vmax. were lower than the corresponding values for l-valyl-l-valine, suggesting a higher apparent affinity for transport and a lower maximal velocity of transport. Ki for the inhibitory effect of l-leucyl-l-leucine on uptake of glycylsarcosine was less than one-half of the Kt for l-leucyl-l-leucine, so that inhibition was stronger than that expected from the apparent affinity for transport obtained from the kinetics of uptake of the inhibitor. In spite of this, l-leucyl-l-leucine was a much less powerful inhibitor of uptake of glycylsarcosine than was l-valyl-l-valine. 3. The results suggest that total uptake of l-leucyl-l-leucine at pH 5 is the result of at least two processes: uptake of intact peptide by one or more mechanisms, and also hydrolysis followed by uptake of free amino acid. At most concentrations, more than half the mediated uptake of l-leucyl-l-leucine was in the form of intact peptide. 4. The results of experiments on competition for uptake between dipeptides were unexpected. l-leucyl-l-leucine could inhibit mediated uptake of intact glycylsarcosine completely, but glycylsarcosine could not cause complete inhibition of mediated uptake of intact l-leucyl-l-leucine. Glycylsarcosine could, however, cause complete inhibition of mediated uptake of intact l-valyl-l-valine, which in turn could cause complete inhibition of mediated uptake of intact l-leucyl-l-leucine. The existence of more than one dipeptide uptake system in the small intestine seems probable.

scholarly journals Studies on a wide-spectrum intestinal dipeptide uptake system in the monkey and in the human

1975 ◽  
Vol 146 (1) ◽  
pp. 133-139 ◽  
Author(s):  
M Das ◽  
A N Radhakrishnan
Keyword(s):  
Amino Acids ◽  
Wide Spectrum ◽  
Intestinal Transport ◽  
Uptake System ◽  
Efflux Rate ◽  
Leucine Uptake ◽  
Dipeptide Uptake ◽  
In Vitro Uptake ◽  
Broad Specificity

1. The intestinal transport of glycine and leucine residues of glycyl-L-leucine was studied in the monkey and in the human in vitro. Uptake of both [14C]glycyl-L-leuine and glycyl-L-[14C]leucine show similar Kt values, but there is a marked difference in the Vmax. values. Preliminary studies suggest that this anomalous difference in the Vmax. values may be due to the greater efflux rate of glycine from the tissue. 2. Arrhenius plots of both [14C]glycyl-L-leucine uptake and glycyl-L-[14C]leucine uptake in the monkey intestine show a discontinuity at about 20 degrees C. The activation energies above and below the discontinuity are similar for both [14C]glycyl-L-leucine uptake and glycyl-L-[14C]leucine uptake. These similarities in uptake characteristics suggest that the dipeptide glycyl-L-leucine is transported as one unit. 3. In the monkey intestine, glycyl-L-leucine uptake is inhibited by a wide variety of dipeptides, including those containing acidic and basic amino acids. The inhibition was shown to be competitive by using four representative dipeptides namely: L-alanyl-L-alanine, L-alanyl-L-leucine, L-glutamyl-L-glutamic acid and L-lysyl-L-lysine. The results strongly suggest that in the monkey intestine there may be a dipeptide-uptake system with an extremely broad specificity. These results were also confirmed in the human in a limited way.

scholarly journals Ontogeny of dipeptide uptake and peptide transporter 1 (PepT1) expression along the gastrointestinal tract in the neonatal Yucatan miniature pig

2012 ◽  
Vol 110 (2) ◽  
pp. 275-281 ◽  
Author(s):  
Matthew G. Nosworthy ◽  
Robert F. Bertolo ◽  
Janet A. Brunton
Keyword(s):  
Small Intestine ◽  
Age Groups ◽  
Peptide Transport ◽  
Peptide Transporter ◽  
Loop Model ◽  
Peptide Transporter 1 ◽  
Proximal Intestine ◽  
Dipeptide Uptake ◽  
Dipeptide Transport

The H+-coupled transporter, peptide transporter 1 (PepT1), is responsible for the uptake of dietary di- and tripeptides in the intestine. Using an in vivo continuously perfused gut loop model in Yucatan miniature pigs, we measured dipeptide disappearance from four 10 cm segments placed at equidistant sites along the length of the small intestine. Pigs were studied at 1, 2, 3 (suckling) and 6 weeks (post-weaning) postnatal age. Transport capability across the PepT1 transporter was assessed by measuring the disappearance of 3H-glycylsarcosine; real-time RT-PCR was also used to quantify PepT1 mRNA. Each of the regions of intestine studied demonstrated the capacity for dipeptide transport. There were no differences among age groups in transport rates measured in the most proximal intestine segment. Transport of 3H-glycylsarcosine was significantly higher in the ileal section in the youngest age group (1 week) compared with the other the suckling groups; however, all suckling piglet groups demonstrated lower ileal transport compared with the post-weaned pigs. Colonic PepT1 mRNA was maximal in the earliest weeks of development and decreased to its lowest point by week 6. These results suggest that peptide transport in the small intestine may be of importance during the first week of suckling and again with diet transition following weaning.

scholarly journals Targeted Disruption of thePEPT2Gene Markedly Reduces Dipeptide Uptake in Choroid Plexus

2002 ◽  
Vol 278 (7) ◽  
pp. 4786-4791 ◽  
Author(s):  
Hong Shen ◽  
David E. Smith ◽  
Richard F. Keep ◽  
Jianming Xiang ◽  
Frank C. Brosius
Keyword(s):  
Choroid Plexus ◽  
Targeted Disruption ◽  
Dipeptide Uptake

scholarly journals Characterization of peptide fluxes into human erythrocytes. A proton-n.m.r. study

1990 ◽  
Vol 267 (1) ◽  
pp. 141-147 ◽  
Author(s):  
J E Odoom ◽  
I D Campbell ◽  
J C Ellory ◽  
G F King
Keyword(s):  
High Capacity ◽  
Transport Processes ◽  
Human Erythrocytes ◽  
Peptide Hydrolysis ◽  
Simple Diffusion ◽  
Analytical Technique ◽  
Peptidase Inhibitor ◽  
Diffusive Fluxes ◽  
Dipeptide Uptake

A new protocol for measuring cellular uptake of dipeptides was developed in which the problem of peptide hydrolysis is obviated by introduction into the cell suspension of a membrane-permeant peptidase inhibitor. The uptake of unlabelled dipeptide is readily monitored so long as some analytical technique is available for measuring the intracellular peptide concentration; in this study we used n.m.r. spectroscopy. Using this protocol, we demonstrated that dipeptide uptake by human erythrocytes occurs by simple diffusion through the lipid bilayer and not via a high-capacity protein-mediated transport system. Substantiating evidence includes demonstration that: (a) the fluxes are slow compared with known protein-mediated transport processes in human erythrocytes; (b) the uptake is not stereospecific; (c) the uptake does not display saturation kinetics; (d) the fluxes are significantly enhanced by butanol; (e) a distinct correlation exists between the size-corrected permeability coefficients of the dipeptides and their calculated n-octanol/water partition coefficients. It is calculated that under normal physiological conditions the diffusive fluxes of circulating plasma peptides into human erythrocytes are too small for these cells to play a significant role in dipeptide catabolism.

Dipeptide uptake by adenohypophysial folliculostellate cells

1996 ◽  
Vol 271 (1) ◽  
pp. C210-C217 ◽  
Author(s):  
C. Otto ◽  
S. tom Dieck ◽  
K. Bauer
Keyword(s):  
Primary Cultures ◽  
Maximum Velocity ◽  
Peptide Transporter ◽  
Michaelis Constant ◽  
Folliculostellate Cells ◽  
S 100 ◽  
Microscopic Studies ◽  
Energy Dependent ◽  
Dipeptide Uptake ◽  
Dipeptide Derivative

Dipeptide uptake was studied in primary cultures from rat anterior pituitaries by use of radiolabeled carnosine and the fluorescent dipeptide derivative beta-Ala-Lys-N epsilon-AMCA (AMCA is 7-amino-4-methylcoumarin-3-acetic acid). Fluorescence microscopic studies revealed that the reporter peptide specifically accumulated in the S-100 positive folliculostellate cells that do not produce any known hormone. The dipeptide derivative was taken up in unmetabolized form by an energy-dependent saturable process with apparent kinetic constants as follows: Michaelis constant, 19 microM; maximum velocity, 5.5 nmol.mg protein-1.h-1. This high-affinity transporter was strongly affected by inhibitors of sodium/proton exchangers and thus appeared to be driven by a proton gradient. Competition studies revealed that the peptide transporter exhibits broad substrate specificity with a preference for hydrophobic dipeptides. In contrast to free amino acids and the pseudotetrapeptide amastatin, tripeptides were also accepted. Compounds without an alpha- and beta-amino group, such as captopril, thiorphan, and benzylpenicillin, did not affect uptake of the reporter peptide, although they were substrates of the well-characterized intestinal and renal dipeptide transporters.

Sign in / Sign up

Export Citation Format

Share Document