Renal γ-glutamyl transpeptidases: Influence of glycosylation on the electrophoretic behavior and molecular weights of their subunits

The molecular weights (Mr) of mammalian renal gamma-glutamyl transpeptidase light subunits vary from 21 to 25 K; a much broader range is seen for the large subunit (51 to 72 K). However, chemical deglycosylation of these enzymes (rat, human, and bovine) yields subunits each of which exhibits identical Mr (41 and 19 K for the heavy and light subunits, respectively), suggesting strong similarity between the peptide backbones of these glycoproteins. Immunological data also indicate homologies between these enzymes. The difference observed in the Mr of native subunits thus seem to be related to the extent and nature of glycosylation of these proteins.