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Updated: Jun 9, 2026

Transmembrane Domain Oligomerization Propensity determined by ToxR Assay
Published on: May 26, 2011
Internally bridging water molecule in transmembrane alpha-helical kink
Masashi Miyano1, Hideo Ago, Hiromichi Saino
1Structural Biophysics Laboratory, RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan. miyano@spring8.or.jp
Abstract:
There are hundreds of membrane protein atomic coordinates in the Protein Data Bank (PDB), and high-resolution structures of better than 2.5 A enable the visualization of a sizable number of amphiphiles (lipid and/or detergent) and bound water molecules as essential parts of the structure. Upon scrutinizing these high-resolution structures, water molecules were found to 'wedge' and stabilize large kink angle (30-40 degrees) in a simple cylindrical model at the transmembrane helical kinks so as to form an inter-helical cavity to accommodate a ligand binding or active site as a crucial structural feature in alpha-helical integral membrane proteins. Furthermore, some of these water molecules are proposed to play a pivotal role of their conformational change to exert their functional regulation.
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