Involved in nucleolar processing of pre-18S ribosomal RNA and ribosome assembly. 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 (By similarity). The WD repeats are grouped into two tandem seven-bladed beta-propeller regions.