Date post: | 17-Jan-2018 |
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The Three Stages of Cell SignalingBy: Madeline Meyer and Carlos Sanchez
ReceptionTransducti
on Response
Why is this important?• Perceive Surroundings• Tissue Repair• Homeostasis• Functioning Immune System
RECEPTION
G Protein-Coupled Receptors (GPCRs)• Cell-surface transmembrane protein, works with G
protein, which binds GTP to make energy• Signal mol.s = ligands (“link” to another mol. to begin
transduction)• Widespread functions, therefore widespread structures
(all similar)
G Protein-Coupled Receptors
Receptor Tyrosine Kinases (RTK)• Enzymatic activity
• Kinase catalyzes transfer of phosphate groups• Tyrosine kinases catalyze transfer of phosphate group
from ATP to amino acid tyrosine on substrate protein• *ONE tyrosine kinase complex can activate > 10
transduction pathways*• Different from G proteins, which activate only 1 pathway each
Evolutionary significance• All G proteins are similarly shaped (with vital
differences)• This means that the G protein likely evolved very early, hence
it plays a large role in signal transduction in many distant organisms
Transduction
Phosphorylation Cascades• Protein Kinases- Starts off the process • One enzyme phosphorylates another,• then another, then another…• Protein Phosphatase lead to• dephosphorylation
Second Messengers- Cyclic AMP• Cyclic Adenosine Monophosphate• Water Soluble- Spread through diffusion• Adenylyl Cyclase & Epinephrine• G proteins
Benefits of Multistep system• Amplification of signal
• More coordinated and regulated
Response
Response• Occurs in nucleus or cytoplasm• Transcription factors• Multiple responses to the same signal• Scaffolding proteins