TYK2 is a member of the Janus kinase (JAK) family of proteins that play a crucial role in signaling pathways involved in the immune response and inflammation. TYK2 is primarily expressed in immune cells such as T cells, natural killer cells, and dendritic cells, where it functions as a key regulator of cytokine signaling. Dysregulation of TYK2 activity has been implicated in various autoimmune diseases and inflammatory disorders, making it a potential target for therapeutic intervention.