One of at least 4 proteins (Era, RbfA, RimM and RsgA/YjeQ) that assist in the late assembly stage of the 30S ribosomal subunit. An accessory protein needed during the final step in assembly of the 30S ribosomal subunit, for assembly of the head region (the 16S rRNA 3' domain) (PubMed:11514519, PubMed:15496525, PubMed:20188109, PubMed:23611982, PubMed:27382067). It may act while Era is associated and before RimP in 30S subunit assembly (PubMed:20188109). Interacts with S19 (PubMed:15496525). Essential for efficient processing of 16S rRNA; a deletion mutant accumulates 17S rRNA (PubMed:9422595). Deletions also do not assemble the head-associated ribosomal proteins correctly (PubMed:23611982, PubMed:27382067). May be needed both before and after RbfA during the maturation of 16S rRNA. It has affinity for free ribosomal 30S subunits but not for 70S ribosomes (PubMed:9226267). Binds 30S ribosomal subunit but not 70S ribosomes (PubMed:9226267). Binds ribosomal protein S19 and probably 16S rRNA (PubMed:15496525). Binds 30S subunit, but not 70S ribosomes (PubMed:9226267). Translation of the mRNA is repressed by a stem-loop in the first 150 nucleotides of its own transcript (PubMed:1569581). Part of the rpsP-rimM-trmD-rplS operon (PubMed:6357787, PubMed:1569581). The PRC barrel domain binds ribosomal protein S19. Disruption causes slow growth, incomplete processing of 17S rRNA, accumulation of 30S and 50S subunits and decreased translational efficiency (PubMed:9226267, PubMed:23611982). Altered levels of ribosomal proteins in 30S subunits; S2, S3, S14 and S21 severely depleted, S5, S7 and S11 are decreased, distortion of rRNA hleix 44 near the decoding center (PubMed:23611982). Slightly different results show ribosomal proteins S2 and S21 not found in 30S subunits, decreased S3, S13 and S14 in 30S subunits (PubMed:27382067). Deletion is partially suppressed by mutations in rpsM, the gene for ribosomal protein S13 (PubMed:9226267, PubMed:15496525), by a mutation in rpsS, the gene for S19 (PubMed:15496525) and also by increased expression of RbfA (PubMed:9422595). Suppressors due to in-frame fusions with rpsP, the upstream gene for ribosomal protein S16 have been isolated (PubMed:11514519). Suppression is probably due to increased expression of RimM; the fusion proteins are found in translationally active 70S ribosomes (PubMed:11514519). Belongs to the RimM family.