The Jak2 SH2 domain lacks a typical phosphotyrosine-binding pocket.

<p>The crystal structure of the SH2 domain of the Src-family kinase Lck bound to a high-affinity phosphotyrosyl peptide (PDB ID 1LCJ) [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0156218#pone.0156218.ref033" target="_blank">33</a>] is superimposed on the Jak2 SH2 domain. The Lck structure is shown as a white ribbon, with the bound phosphopeptide in green. The Jak2 SH2 domain is colored blue. The phosphotyrosine sidechain and selected residues in the binding pocket are shown in stick form. Note that Phe436 in the Jak2 SH2 domain blocks the position that would be occupied by the phenyl group of a bound phosphotyrosine. Labels refer to Jak2 residues.