Subcellular distribution of terminal α-D- and β-D-galactosyl residues in Ehrlich tumour cells studied by lectin-gold techniques

Abstract

We have studied by high resolution in situ light and electron microscopic lectin-gold techniques the subcellular distribution of α- d -Gal residues using the Griffonia simplicifolia I-B 4 isolectin and compared it with that of β- d -Gal residues as detected with the Datura stramonium lectin in Ehrlich tumour cells grown as ascites or monolayer. The microvillar but not the smooth plasma membrane regions were labelled with the Griffonia simplicifolia I-B 4 isolectin whereas both plasma membrane regions were equally well labelled with the Datura stramonium lectin. Elements of the endocytotic/lysosomal system such as coated membrane invaginations and vesicles, early and late endosomes and secondary lysosomes were positive for both α- d -Gal and β- d -Gal residues. A particular feature of Ehrlich tumour cells is an elaborate tubular membrane system located in the pericentriolar region which is labelled throughout by both lectins and represents part of the endosomal system. In the Golgi apparatus labelling with both lectins was observed to commence in trans cisternae which is indirect evidence for a joint distribution of the sequentially acting β1,4 and α1,3-galactosyl-transferases.