Exchange of cystine and glutamate across plasma membrane of human fibroblasts.

Materials-~-[3,3'-~H]Cystine and ~-[2,3-~H]glutamic acid were obtained from Amersham and New England Nuclear, respectively.L- Homocysteic acid, DL-a-aminoadipic acid, and DL-a-aminopimelic acid were purchased from Sigma.DL-oi,e-Diaminopimelic acid (mixture of LL-, DD-, and meso-isomers) was purchased from Calbiochem-Behring.Cell Culture-The cells used were human diploid fibroblasts de-2256