Phosphorylates specifically 'Ser-10' of histone H3 in vitro and colocalizes with phosphorylated histone H3 during mitosis. Associates with cytoskeletal structures that are necessary for cytokinesis and with the microtubule spindle. Colocalizes also with gamma-tubulin and function in microtubule organizing centers (MTOCs). In contrast with the mammalian B-type Aurora, AUR1 has no kinase activity toward 'Ser-28' of histone H3. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts with TPX2. Nuclear membrane in interphase cells, spindle poles at prophase, mitotic spindle from metaphase to telophase and equatorial cell plate at telophase. Abundant in roots, flowers and flower buds, low or absent in expanded leaves, stems and siliques. Peak of expression at mitosis. Phosphorylation at Thr-185 may regulate activity and degradation of AUR1 in a cell cycle dependent manner. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. Aurora subfamily.