Biomaterial Database

Mechanisms of glycyl-L-leucine uptake by guinea-pig small intestine: relative importance of intact-peptide transport. 1980

M Himukai, and T Hoshi

1. Characteristics of glycyl-L-leucine influx across the mucosal border of isolated guinea-pig ileum have been investigated. The influx of the peptide was measured with glycine-labelled or leucine-labelled compounds (Gly*-Leu or Gly-Leu*) and compared with that of a constituent amino acids under various experimental conditions 2. Gly-Leu* influx over a wide range of peptide concentrations. The latter obeyed simple Michaelis--Menten kinetics whereas the former could be described in terms of two saturable components. 3. Total replacement of medium Na with mannitol had no effect on Gly*-Leu influx, while it markedly reduced Gly-Leu* influx to a level slightly greater than Gly*-Leu influx. L-Leucine influx was partially dependent on Na in contrast to glycine influx which was absolutely dependent on Na. 4. Gly*-Leu influx was not inhibited by the simultaneous presence of glycine or L-isoleucine, while Gly-Leu* influx was strongly inhibited by L-leucine and L-isoleucine. Gly-Leu* influx under submaximal inhibition by L-isoleucine was about the same as Gly*-Leu influx. Di- or tri-glycine did not inhibit glycyl-L-leucine influx, while glycyl-L-leucine markedly inhibited diglycine influx, the inhibition being not competitive but of the mixed type. 5. A Michaelis--Menten type relation was observed for the increment in the transmural potential induced by glycyl-L-leucine, L-leucine or the mixture of the dipeptide and L-leucine. In all cases, the values of the maximum potential change were identical, suggesting that a single electrogenic transfer mechanism was operating in these cases. 6. It is concluded that about a half of glycyl-L-leucine influx is mediated by a carrier system for intact glycyl-L-leucine which is independent of sodium, and the other half is transported as L-leucine after membrane surface hydrolysis, part of this component being sodium-dependent and electrogenic. It is also suggested that the carrier sites for glycyl-L-leucine and glycylglycine are very closely located but separated.

UI	MeSH Term	Description	Entries
D007082	Ileum	The distal and narrowest portion of the SMALL INTESTINE, between the JEJUNUM and the ILEOCECAL VALVE of the LARGE INTESTINE.
D007413	Intestinal Mucosa	Lining of the INTESTINES, consisting of an inner EPITHELIUM, a middle LAMINA PROPRIA, and an outer MUSCULARIS MUCOSAE. In the SMALL INTESTINE, the mucosa is characterized by a series of folds and abundance of absorptive cells (ENTEROCYTES) with MICROVILLI.	Intestinal Epithelium,Intestinal Glands,Epithelium, Intestinal,Gland, Intestinal,Glands, Intestinal,Intestinal Gland,Mucosa, Intestinal
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D007930	Leucine	An essential branched-chain amino acid important for hemoglobin formation.	L-Leucine,Leucine, L-Isomer,L-Isomer Leucine,Leucine, L Isomer
D008297	Male		Males
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D005260	Female		Females
D005998	Glycine	A non-essential amino acid. It is found primarily in gelatin and silk fibroin and used therapeutically as a nutrient. It is also a fast inhibitory neurotransmitter.	Aminoacetic Acid,Glycine, Monopotassium Salt,Glycine Carbonate (1:1), Monosodium Salt,Glycine Carbonate (2:1), Monolithium Salt,Glycine Carbonate (2:1), Monopotassium Salt,Glycine Carbonate (2:1), Monosodium Salt,Glycine Hydrochloride,Glycine Hydrochloride (2:1),Glycine Phosphate,Glycine Phosphate (1:1),Glycine Sulfate (3:1),Glycine, Calcium Salt,Glycine, Calcium Salt (2:1),Glycine, Cobalt Salt,Glycine, Copper Salt,Glycine, Monoammonium Salt,Glycine, Monosodium Salt,Glycine, Sodium Hydrogen Carbonate,Acid, Aminoacetic,Calcium Salt Glycine,Cobalt Salt Glycine,Copper Salt Glycine,Hydrochloride, Glycine,Monoammonium Salt Glycine,Monopotassium Salt Glycine,Monosodium Salt Glycine,Phosphate, Glycine,Salt Glycine, Monoammonium,Salt Glycine, Monopotassium,Salt Glycine, Monosodium
D006168	Guinea Pigs	A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.	Cavia,Cavia porcellus,Guinea Pig,Pig, Guinea,Pigs, Guinea
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia