Tyrosine Kinase Linked Receptors (Insulin) Flashcards
state the transduction system and ligands for tyrosine kinase receptors?
ligand stimulated TK
insulin, EGF
state the transduction system and ligands for tyrosine kinase linked receptors?
associate with cytoplasmic TK
growth hormone
state the transduction system and ligands for guanylate cyclase receptors?
ligand stimulated guanylate cyclase
atrial natriuretic polypeptide
state the transduction system and ligands for serine/threonine kinase receptors?
ligand stimulated ser/threo kinase
transforming growth factor beta
state the transduction system and ligands for tyrosine phosphatase?
intrinsic tyrosine phosphatase
unknown
what is an essential feature of the activation of tyrosine kinase containing receptors?
binding of ligand results in dimerisation of receptors
what is PDGF and therefore what is EGF?
dimeric ligand
EGF = monomeric ligand
the dimerised, phosphorylated receptor initiates a series of signal transduction cascades through association with a number of proteins.
state these events?
- altered gene expression via MAP kinase (MAPK)
- activation of Ras
- signalling via PI3 kinase (PI3K)
- activation of PLC-gamma and PLA2
what is the best characterised signal transduction pathway?
MAP kinase
what are RTKs activated by?
growth factors, hormones
what does the activation of RTKs result in?
activation of adaptor protein Ras GTPase
what does Ras do?
induces signal cascade
starts with kinase - RAC
culminated in activation of MAP kinase (MAPK)
what does MAPK activation result in?
translocation into nucleus
phosphorylates diff proteins, inc TF that regulate gene expression
what is Ras?
GTP-binding protein similar to G-alpha subunit of G proteins
how does Ras become activated?
- accelerated by guanine exchange factor (GEF)
- binds to Ras.GDP complex (inactive) —> dissociation of bound GDP
- GTP binds to Ras, releasing GEF (active form)