Molecular dissection of the interaction between hBLT2 and the G protein alpha subunits

Abstract

Leukotriene B4 (LTB4) is a potent chemoattractant for leukocytes and considered to be an inflammatory mediator. Human BLT2 (hBLT2) is a low-affinity G-protein coupled receptor for LTB4 and mediates pertussis toxin-sensitive chemotactic cell movement. Here, we dissected the interaction between hBLT2 and G-protein alpha subunits using GST fusion proteins containing intracellular regions of hBLT2 and various G alpha protein including G alpha i1, G alpha i2, G alpha i3, G alpha s1, G alpha o1, and G alpha z. Among the tested G alpha subunits, G alpha i3 showed the highest binding to the third intracellular loop region of hBLT2 with a dissociation constant (K-D) of 5.0 x 10(-6) M. These results suggest that G alpha i3 has the highest affinity to hBLT2, and the third intracellular loop region of hBLT2 is the major component for the interaction with G alpha i3.