This family represents a group of sequences that are related to ShlB from Serratia marcescens. ShlB is an outer membrane protein pore involved in the Type Vb or Two-partner secretion system where it is functions to secrete and activate the haemolysin ShlA. The activation of ShlA occurs during secretion when ShlB imposes a conformational change in the inactive haemolysin to form the active protein [1].

1: Activation of Serratia marcescens hemolysin through a conformational change. Walker G, Hertle R, Braun V; Infect Immun 2004;72:611-614. PMID:14688146

2: Type V protein secretion: simplicity gone awry?. Desvaux M, Parham NJ, Henderson IR; Curr Issues Mol Biol 2004;6:111-124. PMID:15119822

3: Two-partner secretion in Gram-negative bacteria: a thrifty, specific pathway for large virulence proteins. Jacob-Dubuisson F, Locht C, Antoine R; Mol Microbiol 2001;40:306-313. PMID:11309114