Localization of glycosylation sites in the Golgi apparatus using immunolabeling and cytochemistry

This review summarizes data on the distribution of certain glycosylation steps in the Golgi apparatus as revealed by immunolabeling and lectin techniques. The methodical basis for such investigations was provided by the introduction of the colloidal gold marker system for immunolabeling and the development of new means of tissue processing such as the low-temperature embedding technique using Lowicryl K4M. The application of these techniques together with highly specific antibodies has provided much of the basis for our current understanding of the Golgi apparatus in functional terms. Thus, in many cell types, three Golgi apparatus compartments can be distinguished, whereas in others no such functional subdivision is evident. Investigations on sialyltransferase distribution have also provided direct evidence that GERL is structurally and functionally part of the Golgi apparatus.