Methionine monooxygenase that promotes depolymerization of F-actin by mediating oxidation of residues 'Met-44' and 'Met-47' on actin to form methionine-sulfoxide, resulting in actin filament disassembly and preventing repolymerization (PubMed:23911929, PubMed:23927065). Regulates the disassembly of branched actin networks also by oxidizing ARP3B-containing ARP2/3 complexes leading to ARP3B dissociation from the network. Acts as a key regulator of the SRF signaling pathway elicited by nerve growth factor and serum: mediates oxidation and subsequent depolymerization of nuclear actin, leading to increase MKL1/MRTF-A presence in the nucleus and promote SRF:MKL1/MRTF-A-dependent gene transcription. Does not activate SRF:MKL1/MRTF-A through RhoA (By similarity). H(+) + L-methionyl-[F-actin] + NADPH + O2 = H2O + L-methionyl-(R)-S-oxide-[F-actin] + NADP(+) Interacts with PLXNA4 (PubMed:12110185). Interacts with RAB1B (By similarity). Interacts with MAPK1/ERK2 (PubMed:18241670, PubMed:18590835). Interacts with RAB1B, RAB35, RAB8A, RAB10, RAB13 and RAB15 (in their GTP-bound forms); binding to RAB1B and RAB35 is of low affinity compared to other Rab proteins; binding to RAB1B and RAB35 is of low affinity compared to other Rab proteins; at least in case of RAB8A may bind 2 molecules of RAB8A simultaneously through a high and a low affinity binding site, respectively (By similarity). Expressed only in testis (at protein level). During spermatogenesis, first expressed after meiosis, gradually increases to a maximum at Oakberg's stage 9 and then decreases until it is undetectable when spermatozoa begin to generate flagella (at protein level). The C-terminal RAB-binding domain (RBD)(1796-1945), also described as 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. Truncated N-terminus. Extended N-terminus. Truncated N-terminus.