Fig 5.

Molecular models of the TP and TP-IP chimeric receptors bound to the Gα C-terminal peptide. The residues involved in the interactions are represented as sticks; hydrogen bonds are shown as blue lines. The color representations of the different ICLs are as follows: ICL1, magenta; ICL2, light orange; ICL3, green; and Gα peptide, blue. For clarity, only the intracellular loops (ICLs) are shown. The interactions observed in TP ICL2-WT and TP ICL3-WT and the chimeric TP ICL2B-IP, TP ICL2B-IP-R60L, TP ICL2B-ΔYLYAQ-IP, and TP ICL3B-IP receptors bound to Gα peptide are shown. In the TP ICL2B-IP-R60L model, Leu60 on ICL1 is pointing away from the Gα peptide binding region located between ICL2 and ICL3. Note the loss of the secondary structure in ICL3 of the TP ICL3B-IP chimera compared to the wild-type TP ICL3.