Silicate tetrahedron. A siliconâoxygen tetrahedron is the Si O 4 anionic group, or a silicon atom with four surrounding oxygen atoms arranged to define the corners of a tetrahedron. This is a fundamental component of most silicates in the Earth's crust. siliconâoxygen tetrahedron is the Si O 4 anionic group, or a silicon atom with four surrounding oxygen atoms arranged to define the corners of a tetrahedron.
Best Answer: G proteins are special proteins that help plasma membrane receptors work. Many different signal molecules use G-protein linked receptors, including epinephrine and other hormones. It is part of a second messenger system. How it works is that some chemical messenger binds to the receptor at the membrane.
G proteins are molecular switches that are activated by receptor-catalyzed GTP for GDP exchange on the G protein alpha subunit, which is the rate-limiting step in the activation of all downstream signaling.eterotrimeric G proteins couple the activation of heptahelical receptors at the cell surface to the intracellular signaling cascades that mediate the physiological responses to extracellular stimuli.