Overlapping distribution of two glycosyltransferases in the Golgi apparatus of HeLa cells

Abstract

Thin, frozen sections of a HeLa cell line were double labeled with specific antibodies to localize the frans-Golgi enzyme, β1,4 galactosyltransferase (GalT) and the medial enzyme, N-acetylglucosaminylransferase I (NAGT I). The latter was detected by generating a HeLa cell line stably expressing a myctagged version of the endogenous protein. GalT was found in the trans-cisterna and trans-Golgi network but, contrary to expectation, NAGT I was found both in the medial- and trans-cisternae, overlapping the distribution of GaIT. About one third of the NAGT I and half of the GalT were found in the shared, transcisterna. These data show that the differences between cisternae are determined not by different sets of enzymes but by different mixtures.