Test 4 1201

Test 4 1201 - Test 4 Martin Rodbell and A.G illman Nobel...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Test 4 Martin Rodbell and A.G. illman Nobel prize in medicine and physiology in 1994 Guanine-nucleotide-binding proteins (G proteins) link an extra cellular signal and in intracellular response Before they were finally called G proteins, in contention they were called : N proteins Three components Receptor in the plasma membrane G protein on the intracellular face of the plasma membrane “Effector” element such as an enzyme or ion channel Membrane Receptor Over 1000 G protein coupled receptors (GPCRs) Integral membrane protein with 7 alpha helical regions spanning the membrane(heptahelical) Amino terminus extracellular Carboxy terminus intracellular Fig 11.7a Hetertrimeric G protein Consists of 3 subunits labeled alpha, beta, and gama Interacts with receptor occupied by a signaling molecule Associated with the intracellular face of the plasma membrane When activated interacts with an effector element Diagrams on Moodle
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Effector enzyme(e.g., adenylyl cyclase) Produces an intracellular “second” messenger Adenylyl cylase is and intergral membrane protein Effector Element Ion channel o Controls movement of ions across the plasma membrane G protein- couples signal transduction system components Membrane receptor – G protein- Adenylyl cycalse GCRP Activated by binding of a “first” messenger signal molecule o Hormone o Neurotransmitter Interacts with a G protein Examples of G proteins Gs – stimulatory G protein o Stimulates adenylyl cyclase Gi- inhibitory G protein o Inhibits adenylyl cyclase G olf- olfactory G protein T- transduction, the G protein involved in vision G proteins “Switch” protein Either “on” or “off”
Background image of page 2
Activated by occupied (activated) receptor Consist of 3 subunits(alpha, beta, gamma) GDP is bound to the alpha subunit of the inactive G protein Inactive(“off”):alpha-GDP beta Active(“on”): alpha-GTP+ beta gamma o Alpha subunit with GTP bound to it and a beta gamma dimer Activation of G proteins An activated receptor interacts with the G protein GT replaces GDP on the alpha subunit The G protein dissociated into alpha-GTO and beta gamma dimer The G protein is now “on” Activated G protein subunits Interacts with their target Howis the G protein turned off? GTP is hydrolyzed by GDP Inactivating G proteins Turned “off” when and intrinsic GTP-ase activity of the alpha subunit hydrolyzes GTP to GDP Alpha- GD and the beta gamma dimer reassociate G- protein- coupled signaling
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 08/22/2010 for the course BIOL 1201 taught by Professor Wishtichusen during the Spring '07 term at LSU.

Page1 / 14

Test 4 1201 - Test 4 Martin Rodbell and A.G illman Nobel...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online