Structural and thermodynamic characterization of the TYK2 and JAK3 kinase domains in complex with CP-690550 and CMP-6.

Janus kinases (JAKs) are critical regulators of cytokine pathways and attractive targets of therapeutic value in both inflammatory and myeloproliferative diseases. Although the crystal structures of active JAK1 and JAK2 kinase domains have been reported recently with the clinical compound CP-690550, the structures of both TYK2 and JAK3 with CP-690550 have remained outstanding. Here, we report the crystal structures of TYK2, a first in class structure, and JAK3 in complex with PAN-JAK inhibitors CP-690550 ((3R,4R)-3-[4-methyl-3-[N-methyl-N-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)amino]piperidin-1-yl]-3-oxopropionitrile) and CMP-6 (tetracyclic pyridone 2-t-butyl-9-fluoro-3,6-dihydro-7H-benz[h]-imidaz[4,5-f]isoquinoline-7-one), both of which bind in the ATP-binding cavities of both JAK isozymes in orientations similar to that observed in crystal structures of JAK1 and JAK2.

Expression, purification, and characterization of TYK-2 kinase domain, a member of the Janus kinase family.

The Janus kinase family consists of four members: JAK-1, -2, -3 and TYK-2. While JAK-2 and JAK-3 have been well characterized biochemically, there is little data on TYK-2. Recent work suggests that TYK-2 may play a critical role in the development of a number of inflammatory processes.

Expression, purification, characterization and crystallization of non- and phosphorylated states of JAK2 and JAK3 kinase domain.

Janus-associated kinases (JAKs) play critical roles in cytokine signaling, and have emerged as viable therapeutic targets in inflammation and oncology related diseases. To date, targeting JAK proteins with highly selective inhibitor compounds have remained elusive. We have expressed the active kinase domains for both JAK2 and JAK3 and devised purification protocols to resolve the non-, mono- (Y1007) and diphosphorylated (Y1007 and Y1008) states of JAK2 and non- and monophosphorylated states of JAK3 (Y980).