IcsA, a polarly localized autotransporter with an atypical signal peptide, uses the Sec apparatus for secretion, although the Sec apparatus is circumferentially distributed. L.D. Brandon, N. Goehring, A. Janakiraman, A. W. Yan, T. Wu, J. Beckwith and M. B. Goldberg. Molecular Microbiology 50(1):45-60 (2003). PDF