BIOLOGY 2B03 Lecture Notes - Lecture 6: Conformational Change, Second Messenger System, Triglyceride
1 Sep 2020
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7 membrane spanning domains which consists of seven transmembrane alpha helices that loop through the membrane of the cell. Creates four extracellular segments (e1-e4) that fold in the extracellular space to form the signal-folding domain. Creates four cytoplasmic segments (c1-c4) that fold into an internal domain that interacts with a trimeric g protein. Examples of gpcrs include receptors that initiate stress responses, light activated rhodopsin in the eye, odorant receptors in the mammalian nose, plant growth hormones and the recent discovery of a glucose sensing gpcr system. Looking at gpcr-mediated pathway used in stress response in mammalian cells. Catecholamines are water-soluble signals that circulate in the bloodstream. Most abundant type include epinephrine, norepinephrine and dopamine. Release of epinephrine and norepinephrine hormones from adrenal medulla is part of the fight-or-flight response. Activation of receptor-associated trimeric g-protein and activation of an effector protein called "adenylyl cyclase" that modulates cytosolic concentration of a secondary messenger, camp.
