RTKs

Signal Transduction - Cell Surface Receptor
Bind to extracellular domains of transmembrane receptors that have kinase domains

Regulate the control of growth

Receptor Tyrosine Kinase

Function/Purpose:

• Phosphorylates proteins on the hydroxyl group of tyrosine residues
• Receptor binding causes quaternary changes

Primary Messenger

• Epidermal Growth Factor (EGF)

Mechanism:

• Hormone binding causes dimerization similar to Janus Kinase 2 (JAK2)
  • Kinase is activated via cross phosphorylated

Further Pathways:

Phosphorylation of Grb-2

• Phosphorylation allows Grb-2 binding to Phospohtyrosine residues in RTKs

Grb Recruits Sos

• Protein Sos/Guanine-nucleotide Exchange Facgtor (GEF) binds and activates RAS
  • Reaches the nucleotide binding pocket and opens it up so that GDP can escape and GTP can enter in its place

Sos activates Ras

• RAS is activated and binds to other components of the molecular circuitry leading to more activation of other protein kinases for cell growth

Additional Information: