Janus kinase

In biology, Janus kinases, also known as JAK kinases, are "a family of intracellular tyrosine kinases that participate in the signaling cascade of cytokines by associating with specific cytokine receptors. They act upon stat transcription factors in signaling pathway referred to as the JAK/STAT pathway. The name Janus kinase refers to the fact the proteins have two phosphate-transferring domains."

Subtypes include:
 * TYK2 kinase
 * Janus kinase 1
 * Janus kinase 2
 * Janus kinase 3

Mutation of the JAK2 gene is present in about half of patients with myeloproliferative disorders such as polycythemia vera, essential thrombocythemia, and idiopathic myelofibrosis but not secondary erythrocytosis or chronic myelogenous leukemia.