SPRY4: ProductsSPRY4 (sprouty 4) is a member of the sprouty family of proteins. It blocks tyrosine kinase growth factor activation of the MAPK signaling pathway, possibly through an interaction with either Raf1 or TESK1. Human SPRY4 is 322 amino acids (aa) in length. It contains three SH3-binding domains (aa 3-9; 25-31; 168-174), an NLS (aa 87-93), a PEST sequence (aa 118-133), and a Cys-rich/Zn++-finger domain that binds both TESK1 and Raf1 (aa 182-298). There are two variant isoforms. One is a short form that shows an alternate start site at Met24, while a second shows a 10 aa substitution for aa 120-129, followed by a premature truncation. Over aa 1-177, human SPRY4 is 89% aa identical to canine SPRY4. Mouse SPRY4 is orthologous to the human short form, and shares 90% aa identity with human SPRY4.