A CONSERVED EPITOPE ON NUCLEAR-PORE PHOSPHOPROTEINS REFLECTS CELL-DIVISION STATUS

The nuclear pore complexes mediate the selective nuclear import of pro teins in a signal- and energy-dependent process. We have earlier repor ted the characterization of a monoclonal antibody, Mab E2, that recogn izes a novel class of nuclear pore phosphoproteins involved in signal- binding and protein transport. In the present study, we have analyzed the pattern of immunoreactivity of Mab E2 in cultured rat fibroblasts and have observed significant differences in the expression of epitope s in proliferating and quiescent cells. Furthermore, the common epitop e recognized by Mab E2 is conserved across species, consistent with it s essential role in nuclear protein import.