Non-catalytic component of the C9orf72-SMCR8 complex, a complex that has guanine nucleotide exchange factor (GEF) activity and regulates autophagy. The C9orf72-SMCR8 complex promotes the exchange of GDP to GTP, converting inactive GDP-bound RAB8A and RAB39B into their active GTP-bound form, thereby promoting autophagosome maturation. As part of the C9orf72-SMCR8 complex, stimulates RAB8A and RAB11A GTPase activity in vitro, however WDR42 is shown not be an essential complex component for this function (By similarity). The C9orf72-SMCR8 complex also acts as a negative regulator of autophagy initiation by interacting with the ULK1/ATG1 kinase complex and inhibiting its protein kinase activity. Component of the C9orf72-SMCR8 complex, at least composed of C9orf72, SMCR8 and WDR41. The complex is formed of two protomers, each individually consisting of one molecule each of C9orf72, SMCR8 and WDR41 (By similarity). The protomers homodimerize via an interaction between C9orf72 (via C-terminus) and SMCR8 (via N-terminus) (By similarity). Within each protomer SMCR8 (via DENN domain) acts as a bridging protein between WDR41 (via C-terminus and N-terminus) and C9orf72 (via C-terminus) (By similarity). The C9orf72-SMCR8 complex associates with the ULK1/ATG1 kinase complex.