Binds mRNA; thus facilitating recognition of the initiation point. It is needed to translate mRNA with a short Shine-Dalgarno (SD) purine-rich sequence (By similarity). Belongs to the bacterial ribosomal protein bS1 family. Was originally (PubMed:7721096 and PubMed:8568274) thought to originate from human but is most probably the result of a cDNA library contamination by L.lactis.