Cystine import is the rate-limiting step in glutathione biosynthesis

Cystine import is the rate-limiting step in glutathione biosynthesis. Cysteine can be synthesized within the cell through the trans-sulfuration pathway. However, this pathway is often insufficient in cancer cells and therefore cysteine must be imported. Different transporters are involved in the import of the reduced, cysteine (CySH), and oxidized, cystine (CySSCy) form of this semi-essential AA. The heavy-chain transporter subunit of system xc-light chain (xCT) seems to play a pivotal role in the import of CySSCy, the predominant form of cysteine in circulation. After import, CySSCy is reduced by cystine reductase and used for different purposes including GSH biosynthesis. Import of cysteine can occur via ASCT (alanine/serine/cysteine transporter) and other transporters (x).

Publication

The Central Role of Amino Acids in Cancer Redox Homeostasis: Vulnerability Points of the Cancer Redox Code. (2017) Milica Vučetić, et al. Front Oncol. 2017;7:319. Figure: F2.

Disease mentions