Dynamics of transitional endoplasmic reticulum sites in vertebrate cells

• Published in: Molecular biology of the cell Vol. 11; no. 9; pp. 3013 - 3030
• Main Authors: Hammond, A T, Glick, B S
• Format: Journal Article
• Language: English
• Published: United States The American Society for Cell Biology 01.09.2000
• Subjects: Animals; Cell Cycle; Cell Division; CHO Cells; Cricetinae; Endoplasmic Reticulum - drug effects; Endoplasmic Reticulum - physiology; Endoplasmic Reticulum - ultrastructure; Feedback; Golgi Apparatus - drug effects; Golgi Apparatus - physiology; Golgi Apparatus - ultrastructure; Green Fluorescent Proteins; HeLa Cells; Humans; Luminescent Proteins - analysis; Membrane Proteins - genetics; Membrane Proteins - metabolism; Microscopy, Fluorescence; Microscopy, Video; Microtubules - drug effects; Microtubules - physiology; Microtubules - ultrastructure; Nocodazole - pharmacology; Nuclear Pore Complex Proteins; Recombinant Fusion Proteins - metabolism; Saccharomyces cerevisiae Proteins; Transfection; Vertebrates; Xenopus laevis
• ISSN: 1059-1524; 1939-4586
• DOI: 10.1091/mbc.11.9.3013

A typical vertebrate cell contains several hundred sites of transitional ER (tER). Presumably, tER sites generate elements of the ER-Golgi intermediate compartment (ERGIC), and ERGIC elements then generate Golgi cisternae. Therefore, characterizing the mechanisms that influence tER distribution may shed light on the dynamic behavior of the Golgi. We explored the properties of tER sites using Sec13 as a marker protein. Fluorescence microscopy confirmed that tER sites are long-lived ER subdomains. tER sites proliferate during interphase but lose Sec13 during mitosis. Unlike ERGIC elements, tER sites move very little. Nevertheless, when microtubules are depolymerized with nocodazole, tER sites redistribute rapidly to form clusters next to Golgi structures. Hence, tER sites have the unusual property of being immobile, yet dynamic. These findings can be explained by a model in which new tER sites are created by retrograde membrane traffic from the Golgi. We propose that the tER-Golgi system is organized by mutual feedback between these two compartments.