The Jak-STAT pathway allows signals to be transmitted from the plasma membrane directly to the nucleus
The (Janus) kinase activity is only associated with the receptor (not intrinsic)

The resulting phospho-tyrosines are bound by SH2-containing transcription factors termed STATs (signal transducers and activators of transcription)

Jak-STAT pathway
- Jak enzyme associates with each receptor
- ligand-mediated receptor dimerization and phosphorylation of each other
- trans-phosphorylation of cytoplasmic tails creates SH2 binding sites
- STATs contain SH2 sites bind phosho-tyrosine, STATs become phosphorylated
- STATs activate genes important in cell proliferation
- STATs become phosphorylated by Jaks
- STAT possess both SH2 groups and Phosphotyrosines
- STAT form dimers - migrate to the nucleus, function as transcription factors

G-protein-coupled receptors can drive normal and neoplastic proliferation

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