BIO 330 Lecture Notes - Lecture 19: Guanine Nucleotide Exchange Factor, Cell Membrane, Protein Kinase A
BIO 330 Lecture notes 19:
• Ligands
• signaling molecules (ex: hormones, ions, nuerotransmitters, etc.)
• Receptors
• proteins imbedded in the plasma membrane or in the cell that respond to signaling
ligands
• The 4 types of signalling by extracellular molecules (animals)
• endocrine
• paracrine
• autocrine
• signaling by plasma-membrane attached proteins
• Endocrine (extracellular signaling)
• hormone released by endocrine cells and carried through the blood stream to distal
target cells
• Paracrine (extracellular signaling)
• signaling molecules only affect target cells that are close to the secreting cells
• Autocrine (extracellular signaling)
• cells responding to substances that they themselves release
• Signaling by plasma-membrane bound proteins
• membrane-bound proteins from two different cells interacting
• signal amplification
• a small signal produces many cell responses
• two common classes of plasma membrane receptors
• G-protein coupled receptors
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• Protein kinase receptors
• Intracellular receptors
• inside the cell..... duh
• G-Proteins
• -guanine nucleoside binding protein
• -switches from active to inactive depending on the GTP hydrolyzed
• -GEF: guanine nucleotide exchange factor changes from GDP to GTP
• -GAP: GTPase-activating proteins (hydrolyzes the GTP
• G-Protein Coupled Receptors (GPCR)
• -contain 7 transmembrane domains
• -ligand binds to the extra cellular portion causing a conformational change on the
cytosol part which activates the attachement of the G-protein
• alpha, beta, and gamma subunits --> dissociation of alpha subunit once ligandis bound
• What happens after the alpha subunit dissociates from the G-protein?
• alpha subunit FTP complex binds to and activates adenylyl cyclase and synthesizes
cAMP
• After the GTP is hydrolyzed to GDP, the alpha subunit dissociates and leaves adenylyl
cyclase to revert to its inactive form
• (GDP bound alpha subunit re-associates with beta subunit)
• cAMP molecules are hydrolyzed to AMP by the phosphodiesterase
• cAMP
• cyclic AMP created via adenylyl cyclase
• Activation of Protein Kinase A by cAMP (3)
• composed of 2 regulatory and 2 catalytic subunits. regulatory subunits inhibit catalytic
subunits in the absence of cAMP
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Document Summary
Intracellular receptors inside the cell duh: g-proteins. Switches from active to inactive depending on the gtp hydrolyzed. Gef: guanine nucleotide exchange factor changes from gdp to gtp. Gap: gtpase-activating proteins (hydrolyzes the gtp: g-protein coupled receptors (gpcr) Phosphorylation of the tyr of the innercellular matrix. Cascade signalling of map that signals gene expresssion across nucleus tubulin heterodimers are the building blocks: microtubules (and 2 types, axonemal, 2. cytoplasmic, axonemal microtubules. One alpha tubulin and one beta tubulin form a dimer called alpha beta tubulin dimer. Protofilament is a linear polymer (going up) of alpha beta tubulin dimers. Site where microtubules assemble and initiate and act as an anchor for one end for nucleation (chromosomes) Centrosome: mtoc during interphase that is positioned near the nucleus. Negative ends at the mtoc and positive spreading outward: microtubule-associated motor proteins. Attach to vesicles needed to be transported and walk along the mt.