Januskinase

Janus kinases ( JAK abbreviation ) are cytoplasmic tyrosine kinases ( special enzymes ) which are associated inter alia with cytokine receptors.

Description

( Which was originally called " Just Another Kinase " ) in contrast to receptor tyrosine kinases, cytokine receptors do not own enzyme activity and therefore require the kinases JAK1 and JAK2 to activate intracellular signaling cascades. Docking a signal molecule to the receptor, the JAKs are activated and phosphorylate each other then.

Function

In the present now activated, it can activate the JAK -STAT signaling pathway. JAKs phosphorylate this so-called STAT proteins (signal transducer and activator of transcription ). These are now moving to the nucleus, where it can stimulate the transcription factors, the transcription of specific target genes.

Of the JAK and STAT proteins mediate many cytokines, interferons and interleukins, but also erythropoietin, growth hormone (GH ) and prolactin and leptin their signals.

Janus kinases are named after the two-headed Roman god Janus, the guardian of the gates, as they have two similar protein domains, of which only one is functional.

Janus kinases inhibitors

Janus kinases can be inhibited by so-called Janus kinases inhibitors. Making these substances to the kinase inhibitors. This group of substances includes substances Ruxolitinib and Tofacitinib. Ruxolitinib is used for the treatment of myelofibrosis. Tofacitinib is for the treatment of psoriasis in phase III clinical testing.