Transport of amino acids in gamma-glutamyl transpeptidase-implanted human erythrocytes.
gamma-Glutamyl transpeptidase purified from hog kidney cortex was implanted in the human erythrocyte membrane by incubation of erythrocytes at 37 degrees c with gamma-glutamyl transpeptidase-incorporated dipalmitoyl phosphatidylcholine vesicles. Membranes prepared from these implanted cells exhibited 4- to 5-fold increase in gamma-glutamyl transpeptidase activity. The association/insertion of gamma-glutamyl transpeptidase into erythrocyte membrane was further demonstrated by antibody to gamma-glutamyl transpeptidase. Implantation of gamma-glutamyl transpeptidase into erythrocyte membrane led to stimulation of uptake of glutamate and alanine, which are normally transported at a slow rate in human erythrocytes. The uptake of these amino acids in the implanted system was inhibited by inhibitors (serine-borate and azaserine) of transpeptidase activity as well as by antibody to gamma-glutamyl transpeptidase. These results in the implanted human erythrocytes demonstrate that gamma-glutamyl transpeptidase enzyme can mediate the translocation of amino acids and provide further evidence in support of its postulated role in the transport of amino acids in natural membranes.
D000409:Alanine / Q000097:blood; D000596:Amino Acids / Q000097:blood*; D004912:Erythrocytes / Q000378:metabolism*; D005971:Glutamates / Q000097:blood; D005978:Glutathione / Q000097:blood; D006801:Humans; D008081:Liposomes / Q000097:blood; D008970:Molecular Weight; D010743:Phospholipids / Q000494:pharmacology*; D011510:Proteolipids / Q000097:blood; D005723:gamma-Glutamyltransferase / Q000097:blood*
D000596:Amino Acids; D005971:Glutamates; D008081:Liposomes; D010743:Phospholipids; D011510:Proteolipids; C020485:proteoliposomes; D005723:gamma-Glutamyltransferase; D005978:Glutathione; D000409:Alanine