The interaction of histone-2A and histone-2B was detected by complemented luciferase activity in rice protoplasts. (A) Accumulations of split luciferase fused to histone 2A (NRLuc-H2A), GID1 (NRLuc-GID1), histone 2B (CRLuc-H2B), or SLR1 (CRLuc-SLR1) in rice protoplasts. The cell extracts were analyzed by immunoblot assays using anti-NRLuc or anti-CRLuc antibodies. Equal protein loading was confirmed by coomassie brilliant blue (CBB) staining. (B) Luminescence signals in rice protoplasts expressing combinations of NRLuc-H2A, NRLuc-GID1, CRLuc-H2B or CRLuc-SLR1 in a 96-well plate. The graph shows the mean RLU ± S.E. (n = 3). The accumulated proteins and signal ratio are described at the bottom of the graph. Notice only protoplasts expressing NRLuc-H2A and CRLuc-H2B show RLU that is significantly higher than that of the non-transformed protoplasts.