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.
The versatile trimeric G proteins enable different receptor-hormone complexes to modulate the activity of the same effector protein. In many types of cells, for example, binding of different hormones to their respective receptors induces activation of adenylyl cyclase. In the liver, glucagon and epinephrine bind to different GPCRs, but binding of both hormones activates adenylyl cyclase and thus triggers the same metabolic responses.