They have an estimated 75% protein to rRNA composition compared to prokaryotic ribosomes, where this ratio is reversed.

Another difference between mammalian mitoribosomes and prokaryotic ribosomes is that the latter contain a 5S rRNA.

Among different species, the proteins comprising the mitoribosome differ greatly in sequence, and sometimes in biochemical properties, which prevents easy recognition by sequence homology.

Transcript variants using alternative promoters or polyA sites have been mentioned in the literature but the complete description of these sequences is not available.

This article on a gene on human chromosome 5 is a stub.