Shemanko Lecture 6 Flashcards
Signal transduction and cell signalling, Jak pathway
Most cell signals are extracellular and therefore must what?
Bind a receptor to be functional
Cell signals that can’t pass the membrane must transmit their signal by what?
a change in the receptors confirmation
The signal is ______ in the cell?
amplified
What is signal transduction?
The process by which information from extracellular molecules is translated to be an internal cell signal
What are the two type of signal transduction? Describe them
Electrical communication: cell signal transmitted through gap junctions
Chemical communication: has signals- proteins that reach receptor and then get amplified with the cell to the nucleus
How does receptor based signalling work?
Target cells contain the receptor which binds specific signals (ligands), these receptors can be trans membrane or cytosolic (the ligand must cross the membrane on its own)
What are the different type of cell stimuli?
autocrine/paracrine- The signaling cell and the target cell (which has receptors) are on the same or neighbouring cell (cell produces signal which binds to neighbouring cells)
- In autocrine cells secrete signals to stimulate their own receptor signal transduction
Endocrine signaling- A signal is carried through the body via the blood to target cells throughout the body, for ex: hormones like estrogen and testosterone and prolactin do this
Juxtacrine signaling- Both the ligand and receptor are membrane bound in close proximity
What are the 6 classes of receptors?
G coupled protein receptors
Ion channel receptors
Cell surface receptors
cytokine receptor
receptor tyrosine kinase (RTK)
steroid hormone receptors
What types of extracellular messengers (cell signals) are their?
amino acids and derivatives
Gases, NO and CO
Steroids derived from cholesterol
Eicosanoids
protein ligands (majority)
What are the three element of cell signalling? What are the two paths it can take?
Have signalling molecule, binds to receptor
this can cause effector to bind inside the cell and create a second messenger signal cell which amplifies signal OR
cause proteins in the cytoplasm to bind
both result in activated proteins
Second messengers are what? How do they do what they do?
2nd messengers are small non protein molecules that amplify the signal inside the cell, second messengers bind to proteins of their own-> activate more proteins-> amplify signals
How does signal transduction involving kinases and phosphatases work?
signaling pathways consist of a series of proteins, each protein in the next step is phosphorylated (confirmation of protein changes) by kinase until the target proteins receive a message to alter cell activity
How do proteins become inactive in signal transduction?
through the removal of phosphate groups by phosphatases.
How do proteins become inactive versus active in a signal cascade, explain the reaction?
Protein kinases transfer a phosphoryl group to the next protein in the cascade (ser, Thr, Tyr, His, or Arg can be phosphylated). Protein phosphatase removes it through hydrolysis (get protein and atp seperate again).
What 4 things control signal transduction?
cell types have specific receptors for certain ligands
Timing of docking protein activation
prescence /absecence of docking sites
inhibitory proteins that turn off pathway
