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. This protein appears to have acquired a second function as a laminin receptor specifically in the vertebrate lineage. A 67 kDa form similar to the human laminin receptor (67LR) has been isolated from the cell walls of blastoconidia, but it does not bind laminin. Belongs to the universal ribosomal protein uS2 family.