Component of the cytosolic iron-sulfur (Fe/S) protein assembly (CIA) machinery (PubMed:12970194, PubMed:15660135, PubMed:17401378). Required for maturation of extramitochondrial Fe-S proteins (PubMed:12970194, PubMed:15660135, PubMed:17401378, PubMed:22362766, PubMed:31040179). The NBP35-CFD1 heterotetramer forms a Fe-S scaffold complex, mediating the de novo assembly of an Fe-S cluster and its transfer to target apoproteins (PubMed:17401378, PubMed:22362766). Nucleotide binding/hydrolysis seems to be critcal for loading of Fe-S clusters onto CFD1 and NBP35 (PubMed:22362766). Required for biogenesis and export of both ribosomal subunits, which may reflect a role in assembly of the Fe/S clusters in RLI1, a protein which performs rRNA processing and ribosome export (PubMed:15660135). Binds 4 [4Fe-4S] clusters per heterotetramer. Contains two stable clusters in the N-termini of NBP35 and two labile, bridging clusters between subunits of the NBP35-CFD1 heterotetramer. Heterotetramer of 2 NBP35 and 2 CFD1 chains. Inviable (PubMed:12970194). Decreases cytosolic iron-sulfur (Fe-S) protein assembly (PubMed:31040179). Belongs to the Mrp/NBP35 ATP-binding proteins family. NUBP2/CFD1 subfamily.