Unconventional mechanisms of protein transport to the cell surface of eukaryotic cells
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Updated: Jul 4, 2026

Characterization of Membrane Transporters by Heterologous Expression in E. coli and Production of Membrane Vesicles
Published on: December 31, 2019
Walter Nickel1, Matthias Seedorf
1Heidelberg University Biochemistry Center (BZH) 69120 Heidelberg, Germany walter.nickel@bzh.uni-heidelberg.de
Abstract:
The classical secretion of soluble proteins and transport of integral membrane proteins to the cell surface require transit into and through the endoplasmic reticulum and the Golgi apparatus. Signal peptides or transmembrane domains target proteins for translocation into the lumen or insertion into the membrane of the endoplasmic reticulum, respectively. Here we discuss two mechanisms of unconventional protein targeting to plasma membranes, i.e., transport processes that are active in the absence of a functional Golgi system. We first focus on integral membrane proteins that are inserted into the endoplasmic reticulum but that, however, are transported to plasma membranes in a Golgi-independent manner. We then discuss soluble secretory proteins that are secreted from cells without any involvement of the endoplasmic reticulum and the Golgi apparatus.
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