Required for bud-site selection and cell separation. Also involved in nucleolar processing of pre-18S ribosomal RNA. 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. Present with 16700 molecules/cell in log phase SD medium. Belongs to the WD repeat PWP2 family.