TEL-JAK2(5-19)Tyr314 represents a major binding site for Grb2.

(A) Ba/F3 cells, Ba/F3-TEL-JAK2(4-17), TEL-JAK2(5-19), and TEL-JAK2(5-19)Tyr314Phe cells were depleted of cytokine and then stimulated in the presence (+) or absence (−) of IL-3. IPs were performed using a Grb2 antibody, and tyrosine-phosphorylated proteins were detected by pTyr IB (upper panel). (B) Ba/F3, TEL-JAK2(4-17), TEL-JAK2(5-19), and TEL-JAK2(5-19)Tyr314Phe cells were depleted of cytokine and stimulated with (+) or without (−) IL-3. GST in vitro mixes were performed with 5 μg GST (lanes 1-8) or GST fused to the SH2 domain of Grb2 (lanes 9-16). Tyrosine phosphorylation was assayed by IB with pTyr antibody.