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Activated rhodopsin triggers a signal transduction cascade

Activated rhodopsin triggers a signal transduction cascade. Reminder on Ion Distribution and Transport in Cells. Cells (eukaryotes) divided into a number of membrane-bound compartments. Concentrations in different compartments can be orders of magnitude different.

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Activated rhodopsin triggers a signal transduction cascade

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  1. Activated rhodopsin triggers a signal transduction cascade

  2. Reminder on Ion Distribution and Transport in Cells • Cells (eukaryotes) divided into a number of membrane-bound compartments. • Concentrations in different compartments can be orders of magnitude different. • Proteins (ion channels, transporters) mediate these concentration gradients. • Membrane proteins central to huge range of processes – cell signaling, nerve impulses, nutrient transport, etc.

  3. Ion Channels and Transient Permeability • Channels open in response to a variety of different stimuli. • Key mechanisms are voltage gating, ligand binding-induced gating and mechanical tension in the membrane.

  4. Mwc models of ligand-gated channels

  5. Light-induced hyperpolarization of the rod cell membrane Hydrolysis of cGMP causes cation channels to close Rod cell membrane hyperpolarizes cGMP

  6. Electrical consequences of illumination Each dot in the figure below represents delivery of a very dim pulse of light containing only a few quanta. Voltage responses appear to come in 3 sizes: none, small, and large, representing the detection of 0, 1 or 2 quanta in each flash. The granularity of response to dim light stimuli is evident. http://www.d.umn.edu/~jfitzake/Lectures/DMED/Vision/Retina/ReceptorPotential.html http://webvision.med.utah.edu/book/part-ii-anatomy-and-physiology-of-the-retina/photoreceptors/

  7. Synapse diffusion http://www.colorado.edu/intphys/Class/IPHY3430-200/008sensory.htm

  8. Other examples of synaptic communication

  9. Other examples of synaptic communication

  10. Other examples of synaptic communication

  11. Other examples of synaptic communication

  12. Other examples of synaptic communication

  13. Other examples of synaptic communication

  14. Other examples of synaptic communication

  15. Other examples of synaptic communication

  16. Other examples of synaptic communication

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