Component of the ribosome, a large ribonucleoprotein complex responsible for the synthesis of proteins in the cell. The small ribosomal subunit (SSU) binds messenger RNAs (mRNAs) and translates the encoded message by selecting cognate aminoacyl-transfer RNA (tRNA) molecules. The large subunit (LSU) contains the ribosomal catalytic site termed the peptidyl transferase center (PTC), which catalyzes the formation of peptide bonds, thereby polymerizing the amino acids delivered by tRNAs into a polypeptide chain. The nascent polypeptides leave the ribosome through a tunnel in the LSU and interact with protein factors that function in enzymatic processing, targeting, and the membrane insertion of nascent chains at the exit of the ribosomal tunnel (PubMed:22096102). eS19 is required for proper maturation of the small (40S) ribosomal subunit. Binds to 40S pre-ribosomal particles, probably required after association of NOC4 but before association of ENP1, TSR1 and RIO2 with 20/21S pre-rRNA (PubMed:16159874, PubMed:17726054). Component of the small ribosomal subunit (SSU). Mature yeast ribosomes consist of a small (40S) and a large (60S) subunit. The 40S small subunit contains 1 molecule of ribosomal RNA (18S rRNA) and 33 different proteins (encoded by 57 genes). The large 60S subunit contains 3 rRNA molecules (25S, 5.8S and 5S rRNA) and 46 different proteins (encoded by 81 genes) (PubMed:9559554, PubMed:22096102). Disruption of a single RPS19 gene reduces cell growth; a double disruption is lethal. Depletion experiments show the proteins are required for correct maturation of precursor rRNA to generate the 18S small rRNA. A specific site between the 18S and 5.8S precursors (site A2 in ETS1) is not cleaved in disruption mutants. Partially assembled ribosomes are retained in the nucleolus rather than being exported to the cytoplasm. All effects are exacerbated in the double disruption. Increases association of NOC4 with 20S/21S pre-rRNA, decreases association of ENP1, TSR1 and RIO2 with 20S/21S pre-rRNA. Present with 29000 molecules/cell in log phase SD medium. There are 2 genes for eS19 in yeast. Belongs to the eukaryotic ribosomal protein eS19 family.