Baumrucker C R, Pocius P A, Riss T L
Biochem J. 1981 Jul 15;198(1):243-6. doi: 10.1042/bj1980243.
gamma-Glutamyltransferase (D-glutamyl transpeptidase, EC 2.3.2.2) activity has been shown to be located predominantly on the extracellular surface of the plasma membrane of lactating bovine mammary cells. Radioactive label from both oxidized ([14C]-gamma-glutamyl) and reduced ([35S]cysteinyl) glutathione was taken up and incorporated into acid-precipitable proteins of mammary tissue. Uptake was shown to involve the transport of free amino acids, and incorporation was shown to involve the action of gamma-=glutamyltransferase. These results indicate that lactating mammary tissue utilizes the constituent amino acids of glutathione for milk-protein synthesis.
γ-谷氨酰转移酶（D-谷氨酰转肽酶，EC 2.3.2.2）活性已被证明主要位于泌乳期牛乳腺细胞质膜的细胞外表面。来自氧化型（[14C]-γ-谷氨酰）和还原型（[35S]半胱氨酰）谷胱甘肽的放射性标记物被摄取并掺入乳腺组织的酸沉淀蛋白中。摄取过程涉及游离氨基酸的转运，而掺入过程涉及γ-谷氨酰转移酶的作用。这些结果表明，泌乳期乳腺组织利用谷胱甘肽的组成氨基酸进行乳蛋白合成。
