Abstract
Since UV generally causes a rapid cell death and ionizing radiation induces a delayed form of apoptosis, the activation of signal transduction by radiation would be different between γ-rays and UV. In order to identify the signaling regulators associated with apoptotic cell death, we analyzed cellular proteins responding to γ or UV irradiation using two dimensional gel electrophoresis (2DE). In this study, Jurkat cells were irradiated with 15 Gy of γ-rays or 20 J/m2 of UV, both of which show a similar effect on cell killing, incubated for 48 h or 6 h respectively, and treated with digitonin for preparing their cytosolic extracts. Comparison of the silver stained 2DE protein patterns of the extracts from irradiated and un-irradiated cells showed differences in many spots. These protein spots were classified into three groups proteins; specifically responding to either γ-rays (A) or UV (B), and proteins responding to both radiations (C). Then the protein spots, belonging to the group (C), were digested by trypsin and analyzed by a MALDI-TOF/TOF mass spectrometry. Acidic ribosomal protein P2, Rho GDP dissociation inhibitor β, and initiation factor 5A were identified as a protein responding to both irradiations by means of peptide mass fingerprinting analysis.
