200 likes | 334 Views
Cell to cell communication = Cell signalling.
E N D
Cell to cell communication = Cell signalling Involves a signal molecule secreted from one cell that interacts with receptors on a second cell. The secreted molecule could be a hormone, neurotransmitter, histamine or other substance that either acts locally (paracrine), moves through the bloodstream to another organ (endocrine) or is released by a neuron (synaptic). The molecule binding with the receptor initiates a sequence of events mediated by a g protein that that results in a biological effect. The type of effect depends on the secreted molecule and the cell type; some molecules can have different effects on different cells – the question is how? Ligand (ex insulin, epinephrine)→ Receptor → G protein (GDP to GTP) → adenylyl cyclase→ cAMP (second messenger and signal amplification) → activate protein kinase (several kinds)→ phosphorylate a protein(s) (result in an effect)
Gap junction between two cells (ex muscle) to promote exchange of materials
Signals can either interact at the surface of the cell (protein hormones, growth factors) or inside the cell (steroid hormones, NO)
Different modes of signalling; we will focus on endocrine for now
Good tutorials http://www.prism.gatech.edu/~gh19/b1510/signal.htm http://www.biology.arizona.edu/cell_bio/problem_sets/signaling/overview.html http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/CellSignaling.html This one is a bit advanced but lists all known kinds of cell signalling
http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter17/animation__second_messenger__camp.htmlhttp://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter17/animation__second_messenger__camp.html Good basic introduction to G proteins and cAMP http://highered.mcgraw-hill.com/olc/dl/120069/bio08.swf Signal amplification http://bcs.whfreeman.com/thelifewire/content/chp15/15020.html G protein mediated work of epimephrine and glycogen very good http://www.youtube.com/watch?v=iGb93jCKVXs&feature=related cAMP and kinase example http://highered.mcgraw-hill.com/olc/dl/120069/bio06.swf Intracellular receptors http://vcell.ndsu.edu/animations/insulinsignaling/index.htm Insulin signalling example
Two keys steps for G protein activation/deactiviation: • Exchange of GDP for GTP (controlled by guanine exchange factor (GEF) • Conversion of GTP to GDP (controlled by GTPase activating proteins (GAPs). This step deactivates adenylyl cyclase and stops production of cAMP.
Another g protein mediated signal pathway : IP3 http://gpcr101.wordpress.com/2011/07/21/camppka-and-ip3dagca2pkc-pathway-animations/ http://bcs.whfreeman.com/lodish5e/content/cat_010/13010-01.htm?v=chapter&i=13010.01&s=13000&n=00010&o
What kinds of cell signals use g proteins? G proteins are important in signal transduction regarding hormone function, taste, smell, and cell growth
List of diseases associated with mutations in g proteins: http://themedicalbiochemistrypage.org/signal-transduction.php