This domain forms an 18-stranded beta-barrel pore which is likely to act as an alginate export channel [1].

1: Structural basis for alginate secretion across the bacterial outer membrane. Whitney JC, Hay ID, Li C, Eckford PD, Robinson H, Amaya MF, Wood LF, Ohman DE, Bear CE, Rehm BH, Howell PL; Proc Natl Acad Sci U S A. 2011;108:13083-13088. PMID:21778407