104Lecture11

104Lecture11 - Lecture 11 5/12/11 Background reading: MBOC...

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Lecture 11 5/12/11 Background reading: MBOC 5 th Edition: Chapter 15: Pages 879-886; 904-921 MBOC 4 th Edition: Chapter 15: Pages 831-836; 852-871 Outline: Cell surface receptors G protein-coupled receptors Trimeric G proteins Family of α subunits G S G olf G t Gq Inositol Phospholipid Pathway IP 3 Diacylglycerol Enzyme-linked receptors
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Cell surface Receptors G-protein-coupled Enzyme-coupled In this series of lectures we will consider two main classes: Usually have high affinity (K a > 10 8 ) for their ligands since the ligands are present in very low quantities due to the fact that they are dilute in the blood stream. Four main components involved: Signal Receptor Transducer Intracellular target G-protein-coupled receptors This class of receptors includes a number of proteins that have similarities in sequence and mechanism but react with different ligands. The target protein that is activated as a result of this transduction mechanism is either an enzyme that can change the concentration of a small intracellular mediator (second messenger) or can change the ion permeability of the plasma membrane (by acting as an ion channel).
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G-protein-linked receptors belong to a large superfamily of homologous proteins that all make seven transmembrane passes through the plasma membrane. - signal receptor transducer intracellular target The G protein is the transducer which relays the information that the signal has bound to the receptor across the membrane to the primary intracellular target. The primary target is either a protein that can change the concentration of a second messenger or that can act as an ion channel.
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Trimeric G Proteins Couple receptors to effectors (target enzymes or ion channels) Similarities to monomeric G proteins: GTPases Function as molecular switches by flipping between two states when GTP or GDP is bound
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104Lecture11 - Lecture 11 5/12/11 Background reading: MBOC...

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