Part of the small subunit (SSU) processome, first precursor of the small eukaryotic ribosomal subunit. During the assembly of the SSU processome in the nucleolus, many ribosome biogenesis factors, an RNA chaperone and ribosomal proteins associate with the nascent pre- rRNA and work in concert to generate RNA folding, modifications, rearrangements and cleavage as well as targeted degradation of pre- ribosomal RNA by the RNA exosome. Prevents helicase DHX37 to be recruited before post-A1 state. . This is the function of Ensembl gene identifier ENSG00000143633 (FSAF1, 40S small subunit processome assembly factor 1).