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Lecture

BIOL 2021 Lecture Notes - Guanylyl Cyclase, Sh2 Domain, Cyclic Nucleotide


Department
Biology
Course Code
BIOL 2021
Professor
Julie Clark

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BIOL 2021- April 21st2009
CHAPTER 15: CELL COMMUNICATION III
G PROTEIN REGULATED ION CHANNELS
- Binding directly or indirectly through a cyclic nucleotide
VISUAL CASCADE
- Rod photoreceptors - vertebrates
- Fastest known G protein response
DIM LIGHT VISION
- Photo receptor= rhodopsin= GPCR
- Ligand = light delta in conformation
- Retinal absorbs light

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- II cis retinal (light isomerisation)-> all trans retinal
- in Gt= transduction
- Activates cyclic GMP phosphodiesterase
- cGMP: made by guanylyl cyclase
destroyed by cGMP posphodiesterase
Figure: cGMP
- Dark: high cGMP, ion channels OPEN, depolarized cell, high rate of transmitter
- cGMP gated ion channels
- Light: cGMP decreases, ion channels CLOSE, hyperpolarizes, transmitters decrease, signal to
brain -> light

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Figure: phototransduction
SIGNALLING CASCADE
- Amplification
- One photon of light
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