[A Janus kinase subtype that is involved in signaling from a broad variety of CYTOKINE RECEPTORS. The TYK2 kinase is considered the founding member of the Janus Kinase family and was initially discovered as a signaling partner for the INTERFERON ALPHA-BETA RECEPTOR. The kinase has since been shown to signal from several INTERLEUKIN RECEPTORS. ( MSH )] (UMLS (CSP) C1706299) =Amino Acid, Peptide, or Protein; Enzyme