The molecular determinants in the serpentine type receptors,responsible for its functional coupling with the heterotrimeric G-protein

In the review, data of the literature and own results on the functional coupling between the serpentine type receptors and the heterotrimeric G-proteins are analyzed and summarized. The role of cytoplasmic loops and C-tail domain of the receptors in interaction with G-protein alpha-subunits of different types is discussed. On the basis of theoretical analysis it is shown that the second cytoplasmic loop and the proximal to the membrane segments of the third cytoplasmic loop, containing the main G-protein-coupled molecular determinants, have the cationic nature and can form the helical structures. A molecular model of signal transduction from the receptor to G-protein, based on the electrostatic interactions between the cytoplasmic loops of receptors and receptor-binding regions of G-proteins, is developed.