Send to

Choose Destination
J Mol Biol. 2003 Jun 13;329(4):815-29.

Structure-based analysis of GPCR function: evidence for a novel pentameric assembly between the dimeric leukotriene B4 receptor BLT1 and the G-protein.

Author information

UMR 5074 CNRS, Chimie Biomoléculaire et Interactions Biologiques, Faculté de Pharmacie, 15 avenue Ch. Flahault, BP 14491, 34093 Cedex 05, Montpellier, France.


We produced human leukotriene B(4) (LTB(4)) receptor BLT1 as a recombinant protein in Escherichia coli. This detergent-solubilized receptor displays two states with regard to its affinity for LTB(4): (i) a low-affinity state (K(a)=7.8x10(8)M(-1)) that involves a receptor homodimer (BLT1.LTB(4))(2); we report evidence for a central role of the sixth transmembrane helix in regulating the stability of this homodimer; (ii) a high-affinity state (K(a)=1.3x10(10)M(-1)) upon interaction of the receptor with the heterotrimeric GDP-loaded G-protein, Galpha(i2)beta(1)gamma(2). Association of the G-protein with recombinant BLT1 induces GDP-GTP exchange by the Galpha subunit. These results indicate that isolated BLT1 is fully representative of the in vivo receptor with regard to high-affinity recognition of LTB(4), association with a G-protein and activation of Galpha. Using a combination of mass spectrometry after chemical cross-linking and neutron-scattering in solution with the native complex, we establish unambiguously that only one G-protein trimer binds to a receptor dimer to form the stoichiometrically defined (BLT1.LTB(4))(2):Galpha(i2)beta(1)gamma(2) pentameric assembly. This suggests that receptor dimerization could be crucial to transduction of the LTB(4)-induced signal.

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center