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Updated: Jun 17, 2026

Tracking Single Proteins in Lipid Bilayers Using Fluorescence Microscopy
Published on: December 12, 2025
A single glutamate residue controls the oligomerization, function, and stability of the aquaglyceroporin GlpF
Florian Cymer1, Dirk Schneider
1Institut für Biochemie und Molekularbiologie, ZBMZ, Albert-Ludwigs-Universität Freiburg,Stefan-Meier-Strasse 17, 79104 Freiburg, Germany.
Abstract:
Like many other alpha-helical membrane proteins, the monomeric Escherichia coli aquaglyceroporin GlpF associates within cellular membranes and forms higher-order oligomeric structures. A potential impact of the oligomeric state on the protein function remains enigmatic. We have analyzed the role of residues W42 and E43 in the oligomerization of the E. coli GlpF protein in vitro and in vivo. In contrast to W42, the polar glutamate residue at position 43 appears to be critical for oligomerization. While other polar residues can substitute for the function of E43, replacement of E43 with alanine results in a greatly reduced GlpF oligomerization propensity. The reduced interaction propensity of GlpF E43A correlates with an impaired in vivo function as well as a decreased in vivo stability. Therefore, E43 is critical for the proper oligomerization of GlpF, and protein oligomerization appears to be crucial for the channel function as well as for the in vivo stability of the protein.
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