Cytochemical characteristics of the golgi apparatus

Abstract

Lectinocytochemistry provides a useful tool for localizing subcompartments of the complex reticular apparatus of Golgi. The technique is based on interactions of lectins with glycoconjugates present in the limiting membranes and luminal spaces of Golgi elements. Application of a series of lectins of different sugar specificities permits a differentiation between Golgi subcompartments containing glycoconjugates with different oligosaccharide side chains. These may be a) differnet glycoconjugates or b) glycoconjugates at different stages during synthesis or repair of their glycans. The lectinocytochemical studies with mannose-, glucose-, N-acetyl-glucosamine-, N-acetyl-galactosamine-, galactose-, fucose-, and sialic acid-recognizing lectins revealed predominating patterns that labeled distinct, i.e., cis, medial, trans, and transmost, regions of the Golgi apparatus. A further refinement could be achieved by differential lectin-inhibition that enables a dissection of lectin binding reactions on the basis of their binding affinities. High-affinity binding reactions showed that subcompartments are not necessarily confined to one single Golgi subregion and may change their position from one to another subregion. Some of the patterns observed may be interpreted in relation to certain steps during synthesis and modifications of glycans.

Lectin cytochemistry in the gastrointestinal tract with special reference to glycosylation in the Golgi apparatus of Brunner's gland cells.

“…In fact, the linkage a-GalNAc residues are known, in most instances, to be attached by (3-Ga1 and/or p-GlcNAc, and then oligosaccharide backbones composed of the repetition of (3-Gal and (3-GlcNAc residues are elongated (10,11,21,22,28). In the present study, the s u m , KATAOKA SBA label reappeared in trans-most cisternae and continued to mucous granules, and this result agrees with previous studies which showed that oligosaccharide backbones are often terminated with a-GalNAc (7,10,11,19,22,29). This implies that the terminal a-GalNAc residues are transferred to oligosaccharide backbones in the trans-most Golgi cisternae.…”

“…Labeling with SBA first appeared in cis-Golgi cisternae, implying the transfer of the linkage a-GaWac of 0-linked oligosaccharides. This observation further indicates that the subcellular domain where the initial 0-glycosylation takes place is the cis-Golgi cisternae but not the rough endoplasmic reticulum, which agrees with previous biochemical and cytochemical observations (7,8,19,27). SBA binding disappeared in intermediate cistemae.…”

“…UEA-I label corresponding to a-Fuc residues first appeared in trans-Golgi cisternae in the present and previous studies (6,7,27), suggesting the site of fucosylation. These labels continued to mucous granules, indicating that the mucin of Brunner's gland has a-GlcNAc, a-GalNAc, a-Fuc, and possibly a-Gal as terminal sugars.…”

Down-regulation of membrane glycoprotein in amoeboid microglia transforming into ramified microglia in postnatal rat brain

“…It seems that the internalized plasma membrane constituents (including receptors and ligands) are delivered to the Golgi apparatus (Gonatas et al, 1975;Herzog & Farquhar, 1977;Roth, 1978;Joseph et al, 1979;Thyberg, 1980;Thyberg et al, 1980). A recent study showed that different glycoconjugates either newly synthesized or recycling could be differentiated in the Golgi subcompartments (Pavelka & Ellinger, 1991); these authors demonstrated that the binding sites for Gal-affinity lectins were localized predominantly in the transmost Golgi cisterna. It is therefore significant that the Golgi apparatus in the 'intermediate' ramified cells (cells with long thick processes and cells with thin processes) was stained with GSA I-B4 lectin especially at its trans saccules and trans tubular network.…”

Partitioning of cytoplasmic organelles during mitosis with special reference to the Golgi complex

“…Combined electron microscopic and cytochemical techniques have made it possible to divide the stacks into three major subcompartments-cis, medial, and trans-with distinct differences in composition and function (Farquhar and Palade, 1981;Pavelka and Ellinger, 1991;Roth, 1991;Slot and Geuze, 1983). The Golgi stacks are frequently located in a circumscribed region close to the nucleus and display a close relationship to microtubules radiating from organizing centers associated with the centrosome.…”