A novel genetic system characterized by seven (usually) major proteins, including a ParB homolog and a ThiF homolog, is commonly found on plasmids or in bacterial chromosomal regions near phage, plasmid, or transposon markers. It is most common among the beta Proteobacteria. We designate the system PRTRC, or ParB-Related,ThiF-Related Cassette. This protein family is designated protein F. It is the most divergent of the families.