Cyto Receptors and Signal Transduction

Structure of Cyto Receptors

• Typically consist of two chains
• Each chain has:
  • Extracellular cyto binding domain
  • Intracytoplasmic domain

Interaction with Janis Kinases (Jacks)

• In the absence of cyto, the two chains do not remain associated
• Cyto binding to the receptor stabilizes the heterodimer
• This binding brings together the Jacks bound to the cytoplasmic portions of each chain

Activation Mechanism

• Jack kinases phosphorate the cytoplasmic tails of the cyto receptors
• Signal Transduction and Transcription (Stat) molecules bind to the phosphorated cyto receptor chains
• Stat molecules are themselves phosphorated by the Jacks
• Phosphorylation enables Stats to dimerize
• Dimerized Stats migrate into the nucleus
• In the nucleus, Stats directly activate gene transcription