Fig 2: Analysis of protein fractions from different steps of nuclei isolation. The protein fractions obtained following the main steps of the procedure used for isolation of nuclei from leaves of apple are shown. Equal amounts of proteins (4 µg) from each fraction were loaded on the gel. A) Lumenal-binding protein 2 (BiP2), B) histone H3 and C) plastocyanin (PC) were detected with specific antibodies by western blot analysis. D) Coomassie blue staining of the fractionated proteins separated by polyacrylamide gel electrophoresis. Lane 1: crude extract of proteins from homogenized leaf tissue; lane 2: resuspended pellet of the whole cell lysate obtained following treatment with Triton X-100 and centrifugation; lane 3: nuclei collected from the 60% Percoll layer (see nuclear fraction in Figure 1B); lane 4: the interface fraction of 60% Percoll and 2.5 M sucrose layers in the density gradient containing chloroplasts and unbroken cells (see 60% P/2.5 M S interface in Figure 1B); lane 5: sucrose layer of the density gradient (see 2.5 M sucrose layer in Figure 1B); lane 6: nuclei purified by centrifugation on a 35% Percoll cushion.