Enables SH3 domain binding activity. Predicted to be involved in actin filament reorganization; cell migration; and transmembrane receptor protein tyrosine kinase signaling pathway. Predicted to act upstream of or within cell adhesion. Predicted to be active in cytoplasm and focal adhesion. Predicted to colocalize with plasma membrane. Is expressed in several structures, including alimentary system; brain; genitourinary system; hemolymphoid system gland; and integumental system. Used to study Crohn's disease. Orthologous to human EFS (embryonal Fyn-associated substrate). [provided by Alliance of Genome Resources, Apr 2022]