Lecture 1: Cell communication introduction Flashcards
What are the types of signalling
-Contact dependent: The cell communicates only with the cell’s it synapses to.
For example, Notch pathway signalling in drosophila
-Paracrine: The signalling cell produces a local mediator which has the potential to diffuse a certain amount of distance.
For example, Hedgehog expression stimulating decapentaplegic ligand expression
-Endocrine: The cell releases a hormone which causes a systemic alteration (whole body).
For example, Adnrenaline acting via the adrenergic receptors to produce a range of physiological responses
How can cells respond to signalling
Changes in gene expression.
Changes in cell shape.
Metabolic enzymes altering metabolism
What does the French flag model demonstrate
That different thresholds of the signal can produce different responses
Speed of response
-Changing the structure of an exisitng protein (ion channel: fast induced
- Changing the post translational modification (phosphorylation): quite fast)
- Changing protein levels via gene expression (slower)
What are the two mechanisms of feedback and exmaples
Positive feedback: Notch pathway lateral inhbition
Negative feedback: JAK/ STAT pathway down regulation by SOCS negative regulator
What are the two ways signalling can be regulated
- Signalling by phosphorylation
-Signalling by GTP binding
What are the two major groups of kinases in eukaryotes
-Serine and threonine kinase
-Tyrosine kinase
What are the 4 types of inhbitors
Type 1: Binds to the active conformation of kinase with the aspartate residue of the DFG motif pointing into the ATP-binding pocket
Type 2: Binds and stabalises the inactive conformation of the kinase with the flipped aspartate residue facing outward of the binding pocket
Type 3: Occupies an allosteric pocket that is adjacent to the ATP-binding pocket but does not overlap with it
Type 4: Binds to the allosteric pocket remote from the ATP-binding pocket
