The high-affinity tryptophan uptake transport system in human cells.

Biochem Soc Trans

Komaba Organization for Educational Excellence, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan.

Published: June 2024

The L-tryptophan (Trp) transport system is highly selective for Trp with affinity in the nanomolar range. This transport system is augmented in human interferon (IFN)-γ-treated and indoleamine 2,3-dioxygenase 1 (IDO1)-expressing cells. Up-regulated cellular uptake of Trp causes a reduction in extracellular Trp and initiates immune suppression. Recent studies demonstrate that both IDO1 and tryptophanyl-tRNA synthetase (TrpRS), whose expression levels are up-regulated by IFN-γ, play a pivotal role in high-affinity Trp uptake into human cells. Furthermore, overexpression of tryptophan 2,3-dioxygenase (TDO2) elicits a similar effect as IDO1 on TrpRS-mediated high-affinity Trp uptake. In this review, we summarize recent findings regarding this Trp uptake system and put forward a possible molecular mechanism based on Trp deficiency induced by IDO1 or TDO2 and tryptophanyl-AMP production by TrpRS.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC11346423PMC
http://dx.doi.org/10.1042/BST20230742DOI Listing

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