Together these subunits are composed of 4 RNA species and approximately 80 structurally distinct proteins.

This gene encodes a ribosomal protein that is a component of the 40S subunit.

[6] Mutations in this gene cause Diamond–Blackfan anemia (DBA), a constitutional erythroblastopenia characterized by absent or decreased erythroid precursors, in a subset of patients.

[6] Ribosomal protein S19 has been shown to interact with basic fibroblast growth factor.

[7] RPS19 is also secreted extracellularly and its extracellular oligomers (crosslinked by the transglutaminase Coagulation factor XIII) is also known to bind and probably inhibit Macrophage migration inhibitory factor; though S19 oligomers themselves share MCIP's function as another very strong macrophage chemoattractant and bind to anaphylotoxin C5 receptor[8]