the anti-cancer igm monoclonal antibody pat-sm6 binds with high avidity to the unfolded protein response regulator grp78的抗癌igm单克隆抗体pat-sm6结合高活动性展开监管者grp78蛋白反应.pdf

The Anti-Cancer IgM Monoclonal Antibody PAT-SM6 Binds with High Avidity to the Unfolded Protein Response Regulator GRP78 1 1 1 1,2¤ 2 Zachary Rosenes , Terrence D. Mulhern , Danny M. Hatters , Leodevico L. Ilag , Barbara E. Power , 2 3 1 1 Chris Hosking , Frank Hensel , Geoffrey J. Howlett *, Yee-Foong Mok 1 Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia, 2 Patrys ¨ Ltd, Melbourne, Victoria, Australia, 3 Patrys GmbH, Wurzburg, Germany Abstract The monoclonal IgM antibody PAT-SM6 derived from human tumours induces apoptosis in tumour cells and is considered a potential anti-cancer agent. A primary target for PAT-SM6 is the unfolded protein response regulator GRP78, over-expressed externally on the cell surface of tumour cells. Small angle X-ray scattering (SAXS) studies of human GRP78 showed a two- domain dumbbell-shaped monomer, while SAXS analysis of PAT-SM6 revealed a saucer-shaped structure accommodating five-fold symmetry, consistent with previous studies of related proteins. Sedimentation velocity analysis of GRP78 and PAT- SM6 mixtures indicated weak complex formation characterized by dissociation constants in the high micromolar concentration range. In contrast, enzyme-linked immunosorbant assays (ELISAs) showed strong and specific interactions between PAT-SM6 and immobilized GRP78. The apparent binding constant estimated from