Referenced in: none

Automatically associated channels: Kv10.1

Title: Organization of diphtheria toxin T domain in bilayers: a site-directed spin labeling study.

Authors: K J Oh, H Zhan, C Cui, K Hideg, R J Collier, W L Hubbell

Journal, date & volume: Science, 1996 Aug 9 , 273, 810-2

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/8670424

Abstract
The diphtheria toxin transmembrane (T) domain was spin-labeled at consecutive residues in a helical segment, TH9. After binding of the T domain to membranes at low pH, the nitroxide side chains generated by spin labeling were measured with respect to their frequency of collision with polar and nonpolar reagents. The data showed that the helical structure of TH9 in solution is conserved, with one face exposed to water and the other to the hydrophobic interior of the bilayer. Measurement of the depth of the nitroxide side chains from the membrane surfaces revealed an incremental change of about 5 angstroms per turn, which is consistent with a transmembrane orientation of an alpha helix. These results indicate that the helix forms the lining of a transmembrane water-filled channel.