Required for the assembly and/or stability of the 40S ribosomal subunit. Required for the processing of the 20S rRNA-precursor to mature 18S rRNA in a late step of the maturation of 40S ribosomal subunits. Component of the small ribosomal subunit. Mature ribosomes consist of a small (40S) and a large (60S) subunit. The 40S subunit contains about 33 different proteins and 1 molecule of RNA (18S). The 60S subunit contains about 49 different proteins and 3 molecules of RNA (25S, 5.8S and 5S). Interacts with rps21. Deficiency of 40S ribosomal subunit formation, this is likely to be caused by insufficient 18S rRNA stability. There are two genes for S0 in S.pombe. Belongs to the universal ribosomal protein uS2 family.