Primarily required at the G2/M phase. Essential for viability: involved in nucleolar processing of pre-18S ribosomal RNA as part of the ribosomal small subunit (SSU) processome. Interacts with snoRNA U3. Interacts with MPP10. Component of the ribosomal small subunit (SSU) processome composed of at least 40 protein subunits and snoRNA U3. When overexpressed, has a role in the structure of silenced chromatin. Overproduction causes derepression of gene expression at both HML and HMR, as well as at the rDNA locus and at telomeres. Belongs to the SAS10 family.