Nuclear actin in plants

Actins constitute a wide family of proteins that are major components of the cytoskeleton. Animal cells have nuclear G-actin forms that assemble into several nuclear macromolecular complexes and are substrates for myosin I beta (NMI). The nuclear actin related proteins (ARPs) are part of the chromatin-remodelling complex, while nuclear acting binding proteins (nABPs) comprise either nuclear forms of cytoplasmic ABPs (as NMI) or specific nABPs. No evidence of the presence of nuclear actin exists in plants, which lack orthologues of the main animal structural nABPs. Here we prove the presence of actin forms with different solubility, and their associated protein NMI in the plant nucleus, as components of the transcription complexes and the nucleoskeleton. For this, WB and confocal immunofluorescence with antibodies against human actin and NMI were used.