Members of this protein family are involved in a sec independent translocation mechanism. This pathway has been called the DeltapH pathway in chloroplasts [2]. Members of this family in E.coli are involved in export of redox proteins with a "twin arginine" leader motif [1].

1: A novel and ubiquitous system for membrane targeting and secretion of cofactor-containing proteins. Weiner JH, Bilous PT, Shaw GM, Lubitz SP, Frost L, Thomas GH, Cole JA, Turner RJ; Cell 1998;93:93-101. PMID:9546395

2: Sec-independent protein translocation by the maize Hcf106 protein. Settles AM, Yonetani A, Baron A, Bush DR, Cline K, Martienssen R; Science 1997;278:1467-1470. PMID:9367960