BIOL 2021 Chapter Notes - Chapter 15.6: Guanylyl Cyclase, Cyclic Nucleotide, Rhodopsin
11 Feb 2018
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A g-protein can bind directly to a channel or regulate the ion channel indirectly with an intermediate called a cyclic nucleotide. Cyclic nucleotide gated ion channels are important in smell and vision (ex. rod photoreceptors) Rod photoreceptors are used for dim-light vision in vertebrates (fastest. The outer region is packed full of membrane bound disks where photosensitive rhodopsin molecules are located. The synapse section sends signals to neurons and eventually to the brain. The photoreceptor is a gpcr called rhodopsin (not the same as bacteriorhodopsin h+ pump) that gets activated by a photon of light and causes a conformational change (like the binding of a physical signaling molecule) Retinal: photoreceptor that creates a conformational change in rhodopsin. An isomerization reaction (11cis all trans double bonds) G protein is called gt (transducin) is a g protein that ctivates an enzyme called cyclic gmp phosphodiesterase: breaks phosphodiester bonds: destroys cyclic gmp (cgmp) Vision is created by destroying a cyclic nucleotide (cgmp)
