by Alexander SHPAKOV, Dr. Sc. (Biol.), laboratory head, Molecular Endocrinology Laboratory, Sechenov Institute of Evolutionary Physiology and Biochemistry, St. Petersburg, Russia
Cells live on only if they respond adequately to external signals sent by hormones and growth factors involved mostly in a specific interaction with serpentine receptors in the plasma membrane. Such receptors make use of GTP-binding proteins to get the signal into the cell. The complex natural mechanism of this action calls for great intellectual effort. Therefore any headway in this area is valued high by the world scientific community: four Nobel prizes have been awarded in these last twenty years for progress made. Such breakthrough explorations expand the boundaries of knowledge. And not only that: receptors coupled to GTP-binding proteins are targets for as much as 40 percent medical drugs used today, and so they are naturally in the focus of attention. These last few years have seen new revolutionary technologies for high-selectivity regulators of like receptors ushering in dramatic changes in treating many diseases and on the pharmaceutical market as well.
Cycle of hormonal activation of serpentine receptors and coupled G protein. 1--hormone gets to receptor associated with the G protein; 2-hormone associates with the receptor binding site; 3--receptor and G protein change their conformation, thus lowering the affinity of G protein forguanosine diphosphate (GDP); 4--guanosine triphosphate (GTP) in the G protein a-subunit is substituted for GDP; 5--á-subunit dissociates from the βγ-complex and, acting severally, they activate inferior signaling cascades; 6-α-subunit reduces GTP to GDP, which results in its association with the βγ-complex.
None of the biochemical and physiological processes in man and animals can be out of control. Highly specialized signaling molecules act as their remote control regulators, and th ... Читать далее