Fig. 3.

Membrane topology and structures of the TatA, TatB and TatC proteins. The Tat translocase of E. coli consists of three components, namely TatA, TatB and TatC. TatB and TatC form a receptor complex for cargo proteins, whereas TatA is the main facilitator for protein translocation across the membrane. TatB is missing from the two-component Tat translocases as encountered in B. subtilis. The upper half of the Figure shows a traditional representation of the membrane topology of TatA/E, TatB and TatC based on molecular biological analyses. The lower half of the Figure shows ribbon presentations of the structures of TatA, TatB and TatC as adopted from the RCSB Protein Data Bank (http://www.rcsb.org/structure/). These structures have the following PDB accession codes: TatA—2LZR (solution NMR structure [48]); TatB—2MI2 (solution NMR structure [54]); and TatC—4HTS (crystal structure [63])