This bacterial family of proteins has no known function. The conserved hypothetical protein VC1805 from Vibrio cholerae belongs to this group. It adopts a monomeric assembly, showing an unusual topology with a flat seven-stranded anti-parallel beta-sheet and two helices located on the same side of the sheet. It has some structural homology with the human protein p32 and binds to the complement protein C1q, which suggests a possible role in the adherence of the bacteria to the intestinal wall [1].

1: Crystal structure of VC1805, a conserved hypothetical protein from a Vibrio cholerae pathogenicity island, reveals homology to human p32. Sheikh MA, Potter JA, Johnson KA, Sim RB, Boyd EF, Taylor GL; Proteins. 2008;71:1563-1571. PMID:18300248