Membrane association of FtsY, the E. coli SRP receptor

FtsY, the Escherichia coli homologue of the eukaryotic SRP receptor (SR alpha), is located both in the cytoplasm and in the inner membrane of E. coli. Similar to SR alpha, FtsY consists of two major domains: a strongly acidic N-terminal domain (A) and a C-terminal GTP binding domain (NG) of which the crystal structure has recently been determined. The domains were expressed both in vivo and in vitro to examine their subcellular localization. The results suggest that both domains associate with the membrane but that the nature of the association differs.