This family consists of several TraK proteins from Escherichia coli, Salmonella typhi and Salmonella typhimurium. TraK is known to be essential for pilus assembly but its exact role in this process is unknown [1].

1: Analysis of the traLEKBP sequence and the TraP protein from three F-like plasmids: F, R100-1 and ColB2. Anthony KG, Kathir P, Moore D, Ippen-Ihler K, Frost LS; J Bacteriol 1996;178:3194-3200. PMID:8655498