A novel switch region regulates H-ras membrane orientation and signal output

A1 Journal article (refereed)

Internal Authors/Editors

Publication Details

List of Authors: Abankwa D, Hanzal-Bayer M, Ariotti N, Plowman SJ, Gorfe AA, Parton RG, McCammon JA, Hancock JF
Publication year: 2008
Journal: EMBO Journal
Journal acronym: EMBO J
Volume number: 27
Issue number: 5
Start page: 727
End page: 735
Number of pages: 9
ISSN: 0261-4189


The plasma membrane nanoscale distribution of H-ras is regulated by guanine nucleotide binding. To explore the structural basis of H-ras membrane organization, we combined molecular dynamic simulations and medium-throughput FRET measurements on live cells. We extracted a set of FRET values, termed a FRET vector, to describe the lateral segregation and orientation of H-ras with respect to a large set of nanodomain markers. We show that mutation of basic residues in helix alpha 4 or the hypervariable region (HVR) selectively alter the FRET vectors of GTP- or GDP-loaded H-ras, demonstrating a critical role for these residues in stabilizing GTP- or GDP-H-ras interactions with the plasma membrane. By a similar analysis, we find that the beta 2-beta 3 loop and helix alpha 5 are involved in a novel conformational switch that operates through helix alpha 4 and the HVR to reorient the H-ras G-domain with respect to the plasma membrane. Perturbation of these switch elements enhances MAPK activation by stabilizing GTP-H-ras in a more productive signalling conformation. The results illustrate how the plasma membrane spatially constrains signalling conformations by acting as a semi-neutral interaction partner.


fRET, microdomain, nanocluster, plasma membrane, Ras

Last updated on 2019-23-10 at 03:40