FIGURE 1.

Stefin B in the nucleus co-immunoprecipitates with histones. A, nuclear lysates were prepared as described under “Experimental Procedures” and immunoprecipitated with anti-stefin B antibodies. After SDS-PAGE, gels were stained with Coomassie Blue. The three bands interacting with stefin B were identified as histones by N-terminal amino acid sequencing. N-terminal sequences of the 17- and 14-kDa bands are shown. Track 1, nuclear lysates immunoprecipitated with stefin B antibodies; track 2, molecular weight standard; track 3, control, nuclear lysates immunoprecipitated with antibodies against cathepsin B. B, stefin B co-immunoprecipitates with the H3K4me3 histone variant. Nuclear lysates from T98G cells transfected with stefin B in pEF/Myc/Nuc vector (NB) (track 1) and control T98G cells transfected with an empty vector pEF/Nuk/Myc alone (NO) (track 2) were separated by 15% SDS-PAGE, followed by Western blotting with anti-H3K4me3 antibody. Nuclear lysates from T98G cells transfected with stefin B in pEF/Myc/Nuc vector (NB) (track 3) and nuclear lysates from T98G cells transfected with control empty vector (NO) (track 4), both immunoprecipitated with stefin B antibodies, were separated by 15% SDS-PAGE, followed by Western blotting with anti-H3K4me3 antibody.