Katanin is a heterodimeric microtubule(MT)severing protein that uses energy from ATP hydrolysis to generate internalbreaks along MTs.Katanin p60,one of the two subunits,possesses ATPase and MT-binding/severing activities,and thep 80 subunit is responsible for targeting of katanin to certain subcellular locations.In animals,katanin plays an importantrole in the release of MTs from their nucleation sites in the centrosome.It is also involved in severing MTs into smallerfragments which can serve as templates for further polymerization to increase MT number during meiotic and mitoticspindle assembly.Katanin homologs are present in a wide variety of plant species.The Arabidopsis katanin homolog hasbeen shown to possess ATP-dependent MT severing activity in vitro and exhibit a punctate localization pattern at the cellcortex and the perinuclear region.Disruption of katanin functions by genetic mutations causes a delay in the disappearanceof the perinuclear MT array and results in an aberrant organization of cortical MTs in elongating cells.Consequently,kataninmutations lead to defects in cell elongation,cellulose microfibril deposition,and hormonal responses.Studies of kataninin plants provide new insights into our understanding of its roles in cellular functions.
