RPS3A, also known as 40S ribosomal protein S3a, is a protein that in humans is encoded by the RPS3A gene. It plays a role in ribosomal structure formation and protein binding, participating in protein biosynthesis. Recently, researchers found that the NAL21 gene in rice, which encodes RPS3A, regulates leaf width by modulating the translation levels of growth factor and leaf lateral expansion regulators. This study suggests that appropriate translation regulation of key transcription factors during leaf development is essential for maintaining normal leaf morphology. Moreover, RPS3A has been associated with certain diseases, such as spherocytosis types 1 and 4. It is also involved in pathways related to viral mRNA translation and metabolism.