Receptor Tyrosine Kinase Signaling

Receptor tyrosine kinases transduce signals from growth factors and other ligands by dimerizing and phosphorylating themselves, creating docking sites for intracellular signaling proteins.

Definition

Receptor tyrosine kinase signaling is the process in which a ligand-activated receptor dimerizes and phosphorylates tyrosine residues, generating binding sites that nucleate intracellular signaling complexes.

Scope

This topic covers the structure and activation of receptor tyrosine kinases by ligand-induced dimerization and trans-autophosphorylation, the recruitment of adaptor and effector proteins through phosphotyrosine-binding domains, and downstream pathways such as the Ras–MAP kinase cascade.

Core questions

• How does ligand binding activate a receptor tyrosine kinase?
• Why is autophosphorylation central to creating downstream signals?
• How do adaptor proteins link the receptor to the Ras–MAP kinase pathway?
• How is this signaling amplified and terminated?

Key theories

Dimerization and autophosphorylation activation

Ligand binding brings two receptor molecules together so their kinase domains phosphorylate each other on tyrosines, creating phosphotyrosine docking sites that recruit and activate downstream signaling proteins.

Mechanisms

A ligand such as a growth factor binds the extracellular domain and promotes receptor dimerization, juxtaposing the cytoplasmic kinase domains so they trans-autophosphorylate. The resulting phosphotyrosines are recognized by SH2 and PTB domains of adaptors and enzymes; adaptors such as Grb2 recruit guanine-nucleotide exchange factors that activate the small GTPase Ras, which initiates the MAP kinase cascade and other branches. Phosphatases, GTP hydrolysis, and receptor internalization terminate the signal.

Clinical relevance

These receptors govern cell growth, differentiation, and survival and exemplify how reversible phosphorylation builds signaling complexes, making them a foundational model in cell biology. The treatment here is descriptive and non-prescriptive.

History

The discovery of tyrosine phosphorylation by Hunter and the identification of modular interaction domains by Pawson, together with Schlessinger's work on receptor dimerization, established how receptor tyrosine kinases assemble and propagate signals.

Key figures

• Joseph Schlessinger
• Tony Hunter
• Tony Pawson

Seminal works

• schlessinger2000
• alberts2014

Frequently asked questions

Why do receptor tyrosine kinases need to dimerize?

Pairing two receptors lets their kinase domains phosphorylate each other, which is the step that activates the receptor and creates the docking sites for downstream signaling proteins.

What is the Ras–MAP kinase pathway?

It is a downstream cascade in which the activated receptor leads to activation of the small GTPase Ras, which triggers a chain of protein kinases that ultimately changes gene expression and cell behavior.