Cytokine receptors of the hematopoietin superfamily engage signaling pathways that begin with JAK kinases and lead to activation of STAT-family transcription factors. Each receptor subunit in this superfamily binds a specific JAK kinase (one of four members) and each receptor complex usually activates one major STAT homodimer (one of seven). The specificity for activation of one STAT homodimer by each cytokine is determined by:

Question

Quizplus · Accepted Answer

The specificity for activation of one STAT homodimer by each cytokine is determined by the amino acid sequence surrounding the phosphorylated tyrosine on each cytokine receptor subunit's cytoplasmic tail. This sequence serves as a docking site for specific STAT proteins, which are then phosphorylated by the associated JAK kinase and recruited to the receptor complex. Different cytokine receptors have different amino acid sequences in their cytoplasmic tails, allowing for specific activation of different STATs.

Cytokine Receptors of the Hematopoietin Superfamily Engage Signaling Pathways That