One of the primary rRNA binding proteins, it binds directly to 16S rRNA where it nucleates assembly of the head domain of the 30S subunit. Part of the 30S ribosomal subunit. Belongs to the universal ribosomal protein uS7 family. A mitochondrially-encoded gene whose putative product is 100% identical to the plastid-encoded one is the result of gene transfer. It is not known if that mitochondrial gene is transcribed.