Demonstration of an extensive trans-tubular network continuous with the Golgi apparatus stack that may function in glycosylation |
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| Authors: | Jürgen Roth Douglas J Taatjes John M Lucocq Jasminder Weinstein James C Paulson |
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| Institution: | 1. Interdepartmental Electron Microscopy Biocenter University of Basel CH-4056 Basel, Switzerland;2. Department of Biological Chemistry School of Medicine University of California, Los Angeles Los Angeles, California 90024 USA |
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| Abstract: | Sialyltransferase (Galβ1,4GlcNAc α2,6 sialyltransferase) was localized by immunoelectron microscopy in rat liver hepatocytes using affinity-purified antibodies. Immunoreactivity for sialyltransferase was found in the Golgi apparatus, where it was restricted to an interconnected system consisting of the trans-cisternae and the trans-tubular network. This region of the Golgi apparatus exhibited both TPPase and CMPase activity and was the intracellular site where sialic acid residues bound to glycoprotein were detected using the Limax flavus lectin. Sialyltransferase and sialic acid residues were not detected in medial and cis-cisternae of the Golgi apparatus. These findings suggest that in rat hepatocytes sialylation of N-linked glycoproteins occurs in the complex formed by the trans-cisternae and the trans-tubular network of Golgi apparatus. |
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