The members of this family are sequences that are similar to TraC (Swiss:Q84HT8). The gene encoding this protein is one of a group of genes found on plasmid p42a of Rhizobium etli CFN42 that are thought to be involved in the process of plasmid self-transmission. Mobilisation of plasmid p42a is of importance as it is required for transfer of plasmid p42a, which is also known as plasmid pSym as it carries most of the genes required for nodulation and nitrogen fixation by the symbiotic bacterium. The predicted protein products of p42a are similar to known transfer proteins of Agrobacterium tumefaciens plasmid pTiC58 [1].

1: Conjugative transfer of p42a from rhizobium etli CFN42, which is required for mobilization of the symbiotic plasmid, is regulated by quorum sensing. Tun-Garrido C, Bustos P, Gonzalez V, Brom S; J Bacteriol 2003;185:1681-1692. PMID:12591886