Glutathione utilization by lactating bovine mammary secretory tissue in vitro.
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.
D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D002417:Cattle; D005260:Female; D005978:Glutathione / Q000378:metabolism*; D066298:In Vitro Techniques; D007774:Lactation; D008321:Mammary Glands, Animal / Q000201:enzymology / Q000378:metabolism*; D008894:Milk Proteins / Q000096:biosynthesis; D011247:Pregnancy; D005723:gamma-Glutamyltransferase / Q000378:metabolism
D000596:Amino Acids; D008894:Milk Proteins; D005723:gamma-Glutamyltransferase; D005978:Glutathione