Heme controls the regulation of protein tyrosine kinases Jak2 and Src

► A group of non-membrane spanning tyrosine kinases contain one or more heme-binding CP motifs. ► Protein tyrosine kinases Jak2 and Src are regulated by heme. ► Purified Jak2 and Src can bind to heme directly. ► Heme binding to Jak2 and Src can change their conformation.