Amino Acid Transport Across Mammalian Intestinal and Renal Epithelia

Abstract

The transport of amino acids in kidney and intestine is critical for the supply of amino acids to all tissues and the homeostasis of plasma amino acid levels. This is illustrated by a number of inherited disorders affecting amino acid transport in epithelial cells, such as cystinuria, lysinuric protein intolerance, Hartnup disorder, iminoglycinuria, dicarboxylic aminoaciduria, and some other less well-described disturbances of amino acid transport. The identification of most epithelial amino acid transporters over the past 15 years allows the definition of these disorders at the molecular level and provides a clear picture of the functional cooperation between transporters in the apical and basolateral membranes of mammalian epithelial cells. Transport of amino acids across the apical membrane not only makes use of sodium-dependent symporters, but also uses the proton-motive force and the gradient of other amino acids to efficiently absorb amino acids from the lumen. In the basolateral membrane, antiporters cooperate with facilitators to release amino acids without depleting cells of valuable nutrients. With very few exceptions, individual amino acids are transported by more than one transporter, providing backup capacity for absorption in the case of mutational inactivation of a transport system.

Relationship between [ 14 C]MeAIB uptake and amino acid transporter family gene expression levels or proliferative activity in a pilot study in human carcinoma cells: Comparison with [ 3 H]methionine uptake

“…The amino acid analog MeAIB is an inhibitor and specific substrate for system A amino acid transport and the main transport mechanism for MeAIB uptake is thought to occur via system A [27][28][29][30][31][32].…”

SSRI Augmentation by 5-Hydroxytryptophan Slow Release: Mouse Pharmacodynamic Proof of Concept

“…The mechanism is unclear. Yet, 5-HTP could undergo active transport by large neutral amino-acid transporters present in the colon as well as in the upper intestine (Broer, 2008).…”

Inactivation by Hg2+ and methylmercury of the glutamine/amino acid transporter (ASCT2) reconstituted in liposomes: Prediction of the involvement of a CXXC motif by homology modelling

“…herein]. The study of interaction of mercuric reagents with transport systems for glutamine is still at an initial stage, in spite of the essential role of these transporters in cell homeostasis [25]. It was reported that methylmercury modify the permeability to glutamine of cultured astrocytes by an indirect mechanism based on inhibition of expression of the amino acid transporters ASCT2 and SNAT3; however, this mechanism only partially explained the permeability alteration [26].…”

“…It was reported that methylmercury modify the permeability to glutamine of cultured astrocytes by an indirect mechanism based on inhibition of expression of the amino acid transporters ASCT2 and SNAT3; however, this mechanism only partially explained the permeability alteration [26]. The rat glutamine/amino acid transporter ASCT2 which is expressed in kidney, intestine and nervous system besides other tissues [25], was reconstituted in liposomes [27][28]. The transporter was inserted unidirectionally in the proteoliposomal membrane, right-side-out with respect to the cell membrane; thus, the properties of the internal side of the reconstituted transporter correspond to those of the intracellular side and vice versa.…”