Monooxygenase that promotes depolymerization of F-actin by mediating oxidation of specific methionine residues on actin to form methionine-sulfoxide, resulting in actin filament disassembly and preventing repolymerization. In the absence of actin, it also functions as a NADPH oxidase producing H(2)O(2). Seems to act as Rab effector protein and play a role in vesicle trafficking. Involved in exocytic vesicles tethering and fusion: the monooxygenase activity is required for this process and implicates RAB8A associated with exocytotic vesicles. Required for cytokinesis. Contributes to stabilization and/or maturation of the intercellular bridge independently of its monooxygenase activity. Promotes recruitment of Rab8 and ERC1 to the intercellular bridge, and together these proteins are proposed to function in timely abscission. H(+) + L-methionyl-[F-actin] + NADPH + O2 = H2O + L-methionyl-(R)-S-oxide-[F-actin] + NADP(+) Interacts with RAB1B, RAB8A, RAB10, RAB13 and RAB15 (in their GTP-bound forms); binding to RAB1B is of low affinity compared to other Rab proteins; at least in case of RAB8A can bind 2 molecules of RAB8A simultaneously through a high and a low affinity binding site, respectively. Interacts with ERC1 and RAB8A; may bridge ERC1 with RAB8A. Interacts with KIF23 and ERC1; enhances the interaction between KIF23 and ERC1. Interacts with NINL. Mainly localizes in the nucleus. The bivalent Mical/EHBP Rab binding (bMERB) domain, mediates binding to predominantly Rab8, Rab10, Rab10, Rab13 and Rab15 (in their GTP-bound forms). Belongs to the Mical family. Extended N-terminus.