Predicted tyk2 protein contains two tandem protein kinase domains.

Tyk2 was recently described as an 1187 amino acid protein with a putative protein-tyrosine kinase domain near its C-terminus and no similarity to other proteins in the approximately 900 amino acids preceding the kinase domain. I report here, however, that tyk2 contains an additional protein kinase domain, and that the two tandem kinase domains are preceded by an SH2-like, putative regulatory domain.