lecture 19-W11 - Lecture 19 (2-23-11) Notes I. Introduction...

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Lecture 19 (2-23-11) Notes I. Introduction to cell signaling A. Signaling molecules 1. Released by cells (often by secretion) 2. Can dramatically effect the behavior of cells B. Receptors 1. Allow cells to recognize the presence of a specific signaling molecule 2. Can be on the cell surface or inside the cell C. Four types of cell-cell signaling 1. Contact dependent – cells must be next to each other 2. Paracrine – cells must be in the same neighbor (within 20 cell diameters) 3. endocrine – signals travel throughout the body via the bloodstream 4. synaptic – electrically excited cells communicate at synapses D. The type of signaling molecule determines the type of receptor needed 1. For hydrophilic signals (e.g., peptides, proteins), the receptors must be integral membrane proteins on the surface of cells. 2. For more hydrophobic signals (e.g., steroid hormones), the receptors can be in the cytosol or nucleus of cells. II. G-protein coupled receptor signaling A. What are G-proteins? 1. proteins that bind GTP and hydrolyze it to GDP (they are enzymes) 2. Active when bound to GTP and inactive when bound to GDP (different conformations) 3. many are peripheral membrane proteins found on the cytosolic side of the plasma membrane B. G-proteins can be closely associated with cell surface receptors 1. In the absence of signal, G-protein is in the inactive (GDP-bound) form associated
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This note was uploaded on 02/13/2012 for the course BIO 172 taught by Professor Clark during the Winter '08 term at University of Michigan.

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lecture 19-W11 - Lecture 19 (2-23-11) Notes I. Introduction...

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