Supplementary Figure 6: Mutations in SH2B3 may interfere with JAK2 binding.

Crystal structure of the SH2-B SH2 domain (beige) with JAK2 phosphotyrosine peptide (pTyr813, yellow)25. JAK2 pTyr813 interacts with arginine residues in the SH2-B BC loop. The glutamate residues identified in our association study (Glu395 and Glu400, green) correspond to Glu558 and Glu563 in the SH2-B sequence. They are directly in the BC loop that interacts with JAK2. Glu563 interacts with Arg578.