Eukaryotic striatin forms striatin-interacting phosphatase and kinase (STRIPAK) complexes that control many cellular processes including development, cellular transport, signal transduction, stem cell differentiation and cardiac functions. However, detailed knowledge of complex assembly and its roles in stress responses are currently poorly understood. Here, we discovered six striatin (StrA) interacting proteins, which form a heptameric complex in the filamentous fungus Aspergillus nidulans. The main components are: scaffold StrA (striatin), further components SipA (Mob3), SipB (SIKE-like), SipC (STRIP1/2), SipD (SLMAP), catalytic (SipE, PP2Ac) and regulatory (SipF, PP2AA) phosphatase subunits. The STRIPAK complex, which is established during vegetative growth and maintained during the early hours of light and dark development, is formed on the nuclear envelope in the presence of scaffold StrA. The loss of striatin revealed three STRIPAK subcomplexes: (I) SipA only interacts with StrA, (II) SipB-SipD is found as a heterodimer, (III) SipC, SipE and SipF exist as a heterotrimeric complex.