Lack of functional correlation between gamma-glutamyl transpeptidase and amino acid transport in the lactating mouse mammary gland.

ABSTRACT

Gamma-glutamyl transpeptidase (EC 2.3.2.2) in lactating mouse mammary gland was inhibited by affinity labelling of the tissue with 6-diazo-5-oxo-L-norleucine. Amino acid (L-alanine, L-methionine) uptake by the affinity labelled mammary gland tissue and the control tissue was measured in vitro. Uptake of amino acids by the affinity-labelled tissue was comparable to that of control tissue. These findings suggest that gamma-glutamyl cycle is not involved in amino acid uptake by the mammary gland.