The role of the J domain of SV40 large T in cellular transformation

SV40 large T antigen (TAg)-mediated transformation is dependent on binding to p53 and the retinoblastoma tumor suppressor protein (pRB) and inactivati ng their growth suppressive functions. Transformation minimally requires th ree regions of TAg: a C-terminal domain that mediates binding to p53; the L XCXE motif (residues 103-107), necessary for binding to pRB and the related proteins p107 and p130; and an N-terminal domain (residues 1-82) that cont ains homology to the J domain found in cellular DnaJ/Hsp40 molecular chaper one proteins. We have found that the N-terminal J domain of T Ag cooperates with the LXCXE motif to inactivate the growth suppressive functions of the pRB-related proteins. (C) 1999 The International Association for Biologica ls.