Non-adherent cell-specific expression of DOCK2, a member of the human CDM-family proteins

Human DOCK180, which was originally identified as a major protein bound to the Crk oncogene product, is an archetype of the CDM family of proteins, in cluding Ced-5 of Caenorhabditis elegans and Mbc of Drosophila melanogaster. After DOCK180, at least three putative human proteins that manifest high a mino acid sequence similarity to DOCK180 have been registered in the GenBan k/EMBL database. We have designated one of them, KIAA0209, as DOCK2 and cha racterize here. DOCK2 mRNA was expressed mostly in peripheral blood cells, followed by slight expression in the spleen and thymus, whereas DOCK180 was expressed in all tissues tested except in peripheral blood cells. Immunost aining of human cadaver tissues revealed that the expression of DOCK2 was l imited to the lymphocytes and macrophages of various organs. DOCK2 bound to and activated Rad, as did DOCK180; however, DOCK2 did not bind to CrkII, w hich transduces signals at focal adhesions. Thus, DOCK180 and DOCK2 are reg ulators of Rac and function in adherent and non-adherent cells, respectivel y. (C) 1999 Elsevier Science B.V. All rights reserved.