Involved in the assembly of mitochondrial NADH:ubiquinone oxidoreductase complex (Complex I) at early stages (PubMed:23509070). Interacts with cytosolic Hsp90 to chaperone the Complex I subunit ND-42 in the cytoplasm (PubMed:23509070). Forms a complex including sicily, ND-42 and Hsp83; the complex is necessary to chaperone ND-42 in the cytoplasm before mitochondrial import; the interaction between sicily and ND-42 is direct and occurs preferably between the unprocessed forms in the cytoplasm; the interaction with Hsp83 is direct (PubMed:23509070). Interacts with ND-30; interaction is stronger between the unprocessed forms in the cytoplasm (PubMed:23509070). Expressed in the ventral nerve cord, larval brain, motor neuron axons, imaginal disks, and muscles (at protein level). Belongs to the NDUFAF6 family.