The <i>An</i>STRIPAK complex controls nuclear shuttling of the stress MAPK MpkC and activation of MpkB, which is required for development and SM production.

(A) Expression of three MAPKs, MpkB, MpkA and MpkC-GFP fusions and activation of MpkB in the presence, StrA (+) and absence, StrA (-) of striatin. α-GFP detects GFP fusions, α-SkpA detects SkpA levels as loading control, α-P44/42 recognizes MpkB phosphorylation. StrA (+) represents WT situation where MpkB is phosphorylated. (B) Cellular localization of MpkB in the presence and absence of StrA. (C) Cellular distribution of MpkA under normal growth (16h veg.) and with the cell-wall damage inducing drug (caspofungin 3 μm, 1h postinduction) treated conditions in StrA (+) and StrA (-). (D) Subcellular localization of MpkC under normal, cell-wall damage induced (caspofungin), oxidative (H2O2, 10 mM, 30min) and osmotic stress (Sorbitol, 1 M, 2h) conditions. White arrows show the nuclei. (E) Our model of AnSTRIPAK complex assembly and its role in development and stress responses. AnSTRIPAK is made from three subcomplexes: SipB (SIKE-like)-SipD (SLMAP) heterodimer, SipA(Mob3)-StrA(STRN) heterodimer and the SipC-SipE-SipF (STRIP-PP2AA-PP2Ac) heterotrimer, which assemble on the StrA scaffold on the nuclear envelope. StrA prevents nuclear shuttling of stress MAPK MpkC under no-stress conditions to help it to receive proper stress signals in cytoplasm. StrA also promotes phosphorylation of pheromone response module kinase MpkB, which is required for sexual fruit body formation and SM production. AnSTRIPAK complex assembly and regulation controls asexual and sexual development, SM production and stress responses.