Topic 5: Receptor Tyrosine Kinases Flashcards
what is the different methods of activation for receptor tyrosine kinases?
- cross phosphorylation
- asymmetric kinase domain dimer
explain cross phosphorylation
two kinase domains increasing each others activity of their domains by phospholating the other
explain asymmetric kinase domain dimer
one kinase domain (activator) pushes against another (receiver) causing a conformation change of the receiver and now is phosphorylating things
how does a cell signal is propagated on the inside of the cell after the RTK activation?
by the MAPK pathway
RAS interacts with RAF then it phosphorylates, MEK and then that phosphorylates ERK.
what proteins bind to RTK docking site?
signalling proteins
- SH2 (src homology 2 domain)
- PTB (phosphotryosine binding domain)
what does PTB usually bind to?
Asn-Pro-X-Tyr Motifs
how can RTKs be down regulated?
- receptor mediated endocytosis
- lysosomal degradation
(topic 2 explains them)
what promotes the downregulation?
monoubiquitinylation - the covalent modification of receptors
how is Ras important to RTK and his is it activated by it?
it gets activated by adapter protiens called SOS when the SOS binds to GRB2 (SH2&3)
what acts like the GEF in this pathway
SOS
how is the MAPK pathway activated?
the RTK
what is the purpose of the MAPK pathway?
to control changes in gene expression and protein activity
how is cross talk prevented by different map kinase modules
scaffolding proteins hold them in place so the phosphorylate what they are suppose to
describe the mechanism of Rho signalling through ephorin receptors
Bidirectional/reverse signalling, intracellular signalling is downstream of both the ligand and the receptor
describe the purpose of Rho signalling through ephorin receptors
to grow the growth cone of an axon into a synaptic axon
what kind of mutation would result in a constitutively activated Ras?
the inability to hydrolyze GTP would cause to to stay active
describe energy transference by FRET
Forster Resonance Energy Transfer
- when the donor and acceptor protein are so close together (<10nm) that the intermediate light does not show up as its immediately transferred to the acceptor
