For the sake of thoroughness, it has to be stressed that all the substrates mentioned so far are L-amino acids; however, ASCT2, together with ASCT1, is also responsible for distribution of D-serine in brain whose concentration needs to be kept constant because its alteration is linked to neurological disorder such as ALS (Lee et al., 2017) (see section Involvement in Human Pathology and Interaction With Drugs). Here, SLC1A5 is linked to amyotrophic lateral sclerosis.