Jak and STAT Proteins

The Jak/STAT pathway is fairly basic as it includes only two main components: Janus Kinases (Jaks) and Signal Transducers and Activators of Transcription (STATs). Jaks are non-receptor protein tyrosine kinases that are constitutively associated with the cytoplasmic domain of receptors. STATs are latent transcription factors that reside in the cytoplasm until activated via tyrosine phosphorylation by Jaks, at which time they translocate to the nucleus. In select instances, STAT proteins can also be tyrosine phosphorylated by members of the Src family of kinases. The Jak/STAT pathway facilitates cell proliferation, differentiation, survival, and migration, and is critical for many processes including hematopoiesis, immune cell development, and inflammatory responses.