Essential for oogenesis; required for late follicle cell development. 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 (28S, 5.8S and 5S). Ubiquitously expressed in stage 8 embryos. During oogenesis, expression is located basally in somatic follicular epithelium and in the oocyte at the later stages. Expressed both maternally and zygotically throughout all development. Flies exhibit disappearance of the follicular cells of the ovary and abnormalities of the associated germline derivatives, leading to failure of egg production. Produced by alternative splicing. Belongs to the eukaryotic ribosomal protein eS1 family. Extended N-terminus. Extended N-terminus. Extended N-terminus.