DOCK2 (Dedicator of cytokinesis protein 2) is a member of the DOCK-A family, DOCK180 superfamily of proteins. Its predicted molecular weight is 210kD, although it may run approximately at 190kD in SDS-PAGE. It is found in hematopoietic cell types, and regulates the activity of the GTPases Rac-1 and -2. Human DOCK2 is 1830aa in length. It contains one SH3 domain (aa8-69), a DHR-1 region that localizes DOCK2 to the plasma membrane (aa420-662), and a DHR-2 domain that binds to nucleotide-free GTPases and shows GEF activity (aa1115-1621). There are two isoform variants, one that shows a 38aa substitution for Tyr1405, and a second that shows a start site at Met450 with accompanying deletions of aa462-494 and 630-766, and a 22aa substitution for aa934-1830. Over aa420-642, human DOCK2 shares 96% aa identity to mouse DOCK2.