STUDY OF SURFACE CARBOHYDRATES ON ISOLATED GOLGI SUBFRACTIONS BY FLUORESCENT LECTIN-BINDING AND FLOW-CYTOMETRY

The Golgi complex is a functionally heterogeneous subcellular structur e that plays a key role in the synthesis, maturation, and sorting of n ewly synthesized glycoproteins. Fluorescent lectins have been used ext ensively to analyze surface glycoproteins by now cytometry in whole ce lls and more recently in isolated subcellular organelles, such as mito chondria and chloroplasts, We report here the use of several fluoresce in-isothiocyanate-coqugated lectins to detect and quantify specific su rface sugars by now cytometry on isolated elements from purified cis a nd trans-Golgi fractions from rat liver. Our results show that this ap proach may be useful to study Golgi composition and function, since it may reveal the intensity of specific binding of different lectins to each Golgi fraction and the percentage of elements binding the lectins specifically, Thus we show here that Golgi elements appear homogeneou s in mannose and fucose, whereas galactose and N-acetyl-glucosamine re sidues are more abundant in the trans-Golgi elements. (C) 1995 Wiley-L iss, Inc.