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. 2002 Jul 15;99(15):10156–10161. doi: 10.1073/pnas.152259999

Figure 1.

Figure 1

Nuclear import of histone H1 requires energy of ATP and is not supported by nonhydrolyzable ATP or GTP analogs. Nuclear transport of fluorescein-tagged histone H1 was monitored by laser confocal microscopy after microinjection of H1 into the cytosol of neonatal cardiomyocytes. Cellular ATP/GTP levels were depleted by a 30-min treatment (37°C) with the mitochondrial uncoupler, FCCP (1 μM), and the inhibitor of glycolysis, DOG (6 mM). H1 is transported in the nucleus of control (A), but not ATP/GTP-depleted (B) cells. Microinjection into ATP/GTP-depleted cells of nonhydrolyzable ATP and GTP analogs, AMPPNP (C) or GppNHp (D), failed to rescue nuclear import of H1. Vertical bars = fluorescence scale of 0–255 arbitrary units, with red indicating lowest and white indicating highest intensity. (A–D) Magnification = 10 μm.