May be involved in intracellular signaling through interaction with PtdInsPs and calmodulin (CaM); may keep PtdInsPs attached to the plasma membrane until Ca(2+)-CaM reaches a competitive concentration subsequent to an increase triggered by a stimulus, thus leading to PtdInsPs release and subsequent activation of InsPs-dependent signaling cascade (Probable). Binds to microtubules and inhibits tubulin polymerization. Regulates directional cell growth and cortical microtubule organization by destabilizing microtubules (e.g. in cotyledon pavement cells) (PubMed:17337629). Binds microtubules (PubMed:17337629). Interacts with calcium ion Ca(2+), calmodulin and some phosphatidylinositol phosphates (PtdInsPs) such as phosphatidylinositol 3,5-bisphosphate [PtdIns(3,5)P(2)], PtdIns(4,5)P(2) and PtdIns(3,4,5)P(3) (PubMed:20061304). Localized along cortical microtubules as patches of dot-like structures. Mostly expressed in the expanding cells, specifically in roots (except in root tips) and flowers (at protein level). Also detected in cotyledons, hypocotyls and trichome stalks. Expressed in developing root hairs and elongating pollen tubes. By arsenate As (V) (PubMed:18684332). Accumulates in response to abscisic acid (ABA), gibberellic acid (GA), cold, and drought stresses. Induced by various salt treatments such as NaCl, KCl, MgCl(2), MnCl(2) and ZnCl(2) (PubMed:20061304). Expressed during leaf senescence (PubMed:20966154). Altered cortical microtubule arrays. Abnormal cotyledon pavement cells with fewer extension lobes and shorter cell length. Belongs to the DREPP family.