Receptor Tyrosine Kinase
RECEPTOR TYROSINE KINASES
- Are enzymes that add phosphate to tyrosine residues
- Largest subset of the enzyme-coupled receptor class of cellular receptors
- Usually have only one transmembrane segment
- Can activate multiple different signal pathways at once
Steps of Receptor Tyrosine Kinase Pathway
1) Ligand binds to receptor
2) Receptors dimerize
3) Dimerization causes tyrosine kinase domains to become activated
4) Each tyrosine kinase domain adds phosphate to a tyrosine on the other receptor which is bound by an intracellular signal protein
5) Phosphorylated tyrosine residues activate intracellular signal proteins
6) Each activated intracellular signal protein triggers an intracellular signaling pathway
When Ras is involved, the next steps in the pathway are as follows:
7) Intracellular signal protein causes Ras to exchange GDP with GTP
8) GTP-bound Ras is now activated and able to generate a cellular response