血球細胞特異的に発現するM-DOCK蛋白の機能の解析 Analysis of Hematopoietic Cell Specific Protein, M-DOCK
Analysis of Hematopoietic Cell Specific Protein, M-DOCK
Full length cDNA of M-DOCK was isolated at Kazusa DNA Institute and its sequence has been deposited as KIAA0209. The cDNA sequence of M-DOCK contained a 5490 bp open reading frame that encodes a 1830-aa protein with a calculated molecular mass of 212kDa. The amino acid sequence of M-DOCK shows 62.3 % identity with DOCK180 when the carboxyl terminal variable regions were omitted. DOCK180, which was originally identified as a major protein bound to Crk oncogene product, is an archetype of a family of proteins including Ced-5 of C. elegans and Mbc of D. melanogaster. DOCK180 localizes at focal adhesions and regulates cell morphology through the activation of Rac. Expression of DOCK180 is ubiquitous except hematopoietic cells. Here, we report on the characterization of M-DOCK protein, which is closely related to DOCK180 and expressd only in the hematopoietic cells. We immunized rabbits with bacterially-expressd GST-M-DOCK protein, and obtained an anti-sera specific to M-DOCK. Tissue distribution of M-DOCK was exmined by Northern blotting and Western blotting. M-DOCK was expressed abundantly in peripheral blood leukocytes. When cell lines were analyzed, M-DOCK expression wes detected in cells derived from T-cells, B-cells, and monocytes, but never in the adherent cells. Most of lymphocytes and macrophages in human organ expressed M-DOCK diffusely in the cytoplasm analyzed by immunohistochemstry using anti-M-DOCK antibody. We previously reported that memberane-targeted from of DOCK180 induced spreading of NIH 3T3 cells. By contact, overexpression of M-DOCK rounded up flat NRK cells. This suggests that M-DOCK may regulate cell detachment of adherent cells. These results demonstrate that M-DOCK is a new member of DOCK180-family proteins and regulates cell shape in suspension cells.
Hokkaido University（北海道大学）. 博士(医学)