Enhancement of Epstein-Barr virus/C3d receptor (EBV/C3dR or CR2) and nuclear p120 ribonucleoprotein phosphorylation by specific EBV/C3dR ligands in subcellular fractions of the human B lymphoma cell line, Raji.

We present herein the first evidence that interaction of specific EBV/C3dR ligands, as human C3bi/C3d and anti-EBV/C3dR MoAb, with EBV/C3dR enhanced significantly, in a dose dependent process, phosphorylation of EBV/C3dR and p120 RNP present in subcellular fractions, as purified plasma membranes and nuclei, of the human B lymphoma cell line, Raji. The use of kinase effectors allowed to detect some of the kinases involved in these phosphorylations. Pp60src-like phosphotyrosine kinase and protein kinase C were involved in the phosphorylation of plasma membrane or nuclear EBV/C3dR. An additional calcium/calmodulin-dependent kinase was also involved in nuclear EBV/C3dR phosphorylation. P120 RNP phosphorylation was under the control of protein kinase C and of CaCl2/Calmodulin-dependent kinase but also of casein kinase II.