Acts as a nucleation-promoting factor (NPF) that stimulates Arp2/3-mediated actin polymerization both at the Golgi apparatus and along tubular membranes. Its activity in membrane tubulation requires F-actin and interaction with microtubules. Proposed to use coordinated actin-nucleating and microtubule-binding activities of distinct WHAMM molecules to drive membrane tubule elongation; when MT-bound can recruit and remodel membrane vesicles but is prevented to activate the Arp2/3 complex. Involved as a regulator of Golgi positioning and morphology. Participates in vesicle transport between the reticulum endoplasmic and the Golgi complex. Required for RhoD-dependent actin reorganization such as in cell adhesion and cell migration. Interacts with ACTR3; indicative for an association with the ARP2/3 complex. Associates with microtubules; in vitro binds to tubulin heterodimer in a 1:1 stoichiometry; decorates microtubules with a repeat of 80 A along protofilaments. Interacts with RHOD (in GTP-bound form). Localized to a perinuclear compartment near the microtubule-organizing center (MTOC). Also detected on tubulo-vesicular structures in the cell periphery that frequently localized along microtubules. Expressed in brain, lung, heart, colon and kidney (at protein level). The N-terminal region associates with membranes, the coiled-coil region binds to microtubules and the WH2 domains promotes actin nucleation. Extended N-terminus. Truncated N-terminus. Unlikely isoform. Aberrant splice sites.