Janus kinase

Janus kinase (short JAK) is a family of intracellular tyrosine kinases, ranging from 120-140 kDa, that are involved in the signalling cascade of cytokines by associating with one of the cytokine receptors[?], for example, the interferon receptor.

The kinase was named after Janus, the Roman[?] gatekeeper of heaven. He is described as having two faces, as the kinase has two phosphate-transferring domains. The abbreviation JAK is sometimes interpreted as "just another kinase".

See also: JAK-STAT pathway[?]