RTK and signal induction - Haifizi Flashcards
What is signal transduction
The process by which cells convert extracellular signal to a response.
What 3 main ways that signal transduction starts
Cell-Cell communication
Cell’s response to environment
Intracellular homeostasis (internal communication )
What is the difference between autocrine and paracrine chemical systems
Autocrine: cell secretes chemical messenger which then has an effect on the cell it’s self
paracrine: cell secretes chemical messenger that affects cells nearby
What chemical systems are involved in cell-cell communication
Autocrine and paracrine (local)
Endocrine (distant, diffuse target)
What are the steps in the signal pathways
- signal molecule such as ligand binds to receptor protein
- binding activates a pathway or intracellular signalling mediators
- these signalling mediators act on target proteins
- target protein causes a response in the cell
give examples of signal molecules that have ligand -receptor interactions
Peptides/proteins, e.g. growth factors, vasoconstrictors
Amino acid derivatives - epinephrine, histamine
Other small biomolecules - ATP
Steroids, prostaglandins
Gases e.g. nitric oxide (NO)
Photons
Damaged DNA
Odorants, tastants
What two locations can receptors be located in a cells
Cell membrane receptors
Cytosolic/ nuclear receptors
What are the properties of cell membrane receptors
Lipophobic ligands cant enter the cell
Found in the outer surface membrane
Have a fast response
What are the properties of cytosolic/nuclear receptors
Lipophilic ligands enter
Often regulated gene expression
slower response
What are the different types of membrane receptors
Ligand binding which opens or closes channels
Ligand binding activates intracellular enzymes.
ligand binding to G proteins opens an ion channel or alters enzyme activity
Ligand binding to integrin receptors alters the cytoskeleton
What are the steps in signal transduction
Signal binds to the receptors
initiates signal transduction via proteins
leads to enzyme amplification
Second messengers molecules leads to
increased Ca2+ or Protein kinases
Increase Ca2+ leads to calcium-bind proteins then cell response
protein kinases leads to phosphorylated protein leading to cell response
what are kinases
enzymes that phosphorylate substrates
so they catalyse the transfer of a phosphate group from ATP to the substrate
list the signalling proteins that are pro-oncogenes
Serine/Threonine kinase
-Raf
-Akt
Non-receptors tyrosine kinases
-Src
-Abl
GTP-binding proteins
-Ras
What are RKTs
receptor tyrosine kinases are also GF proteins
What two molecules are similar in structure which helped to determine the mechanism of RTK cancers
Oncogenic retrovirus (gene) and EGFR
