This family consists of several hypothetical proteins of unknown function which appear to be found largely in Helicobacter pylori. The structure of HP0721 protein consists of a bundle of four alpha-helices connected by loops and stabilised by hydrophobic interactions. It has been suggested that this protein might represent a novel H. pylori [1].

1: Crystal structure of HP0721, a novel secreted protein from Helicobacter pylori. Cioci G, Terradot L, Dian C, Mueller-Dieckmann C, Leonard G; Proteins. 2011;79:1678-1681. PMID:21365686