Component of the cytosolic iron-sulfur (Fe/S) protein assembly (CIA) machinery. Required for maturation of extramitochondrial Fe-S proteins. 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. 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