rRNA-processing protein UTP23 homolog, also known as UTP23, is a small subunit (SSU) processome component. The SSU processome is a complex involved in ribosome biogenesis and is required for pre-18S rRNA maturation. UTP23 is required for the first three cleavage steps in 18S rRNA maturation. In addition, single-point mutations in the conserved putative active site of Utp24 but not Utp23 abrogate its function in ribosome biogenesis. Recombinant human UTP23 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.