Tyrosine kinase of the non-receptor type, involved in the IFN-alpha/beta/gamma signal pathway (PubMed:7615558, PubMed:28111307, PubMed:32750333, PubMed:16239216). Kinase partner for the interleukin (IL)-2 receptor (PubMed:11909529) as well as interleukin (IL)-10 receptor (PubMed:12133952). Directly phosphorylates STAT but also activates STAT signaling through the transactivation of other JAK kinases associated with signaling receptors (PubMed:16239216, PubMed:32750333). ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Mn(2+) was used in the in vitro kinase assay but Mg(2+) is likely to be the in vivo cofactor. Interacts with IL31RA (PubMed:15194700). Interacts with IFNAR2 (PubMed:7759950). Interacts with IFNGR1 (PubMed:7615558). Interacts with JAKMIP1 (PubMed:15277531). Interacts with SHB (PubMed:12200137). Interacts (via N-terminus) with IL2RB and IL10RA (via its cytoplasmic domain) (PubMed:12133952). Interacts with FER (By similarity). Wholly intracellular, possibly membrane associated. Expressed at higher levels in primary colon tumors than in normal colon tissue. The expression level in metastatic colon tumors is comparable to the expression level in normal colon tissue. The protein kinase 1 domain is also called the pseudokinase domain and has a regulatory role through the transactivation of other JAK kinases associated with signaling receptors. The protein kinase 2 domain is the catalytically active domain. The FERM domain mediates interaction with JAKMIP1. Autophosphorylated (PubMed:7615558). Phosphorylated on tyrosine residues in response to interferon gamma signaling (PubMed:7615558). Dephosphorylation of Tyr-1034 and Tyr-1035 by PTPN2 negatively regulates cytokine-mediated signaling (PubMed:11909529). Ubiquitinated by RNF125; leading to its degradation by the proteasome. The disease is caused by variants affecting the gene represented in this entry. Belongs to the protein kinase superfamily. Tyr protein kinase family. JAK subfamily. Truncated N-terminus.