Multiple forms of gamma-glutamyltransferase and lipoproteins.

The gamma-glutamyltransferase isoenzyme patterns originating from human serum and homogenates of liver, kidney, pancreas and intestine in the presence and in absence of isolated lipoproteins has been studied. On the basis of these results one can conclude that the distribution of a variety of gamma-glutamyltransferase activities obtained by the electrophoresis of blood serum is not a consequence of an existence of a large number of true isoenzymes, but of increased concentrations of lipoproteins which bind to the enzyme thus causing the appearance of gamma-glutamyltransferase in the region of the appropriate lipoproteins.