This entry represents one of two distinct types of extracellular domain found in the 7TM-DISM (7TM Receptors with Diverse Intracellular Signalling Modules) bacterial transmembrane proteins [1]. It is possible that this domain adopts a jelly roll fold and acts as a receptor for carbohydrates and their derivatives [1]. It can also recognise Ca(II) (Matilla et. al., FEMS Microbiology Reviews, fuab043, 45, 2021, 1. https://doi.org/10.1093/femsre/fuab043).

1: Application of comparative genomics in the identification and analysis of novel families of membrane-associated receptors in bacteria. Anantharaman V, Aravind L; BMC Genomics 2003;4:34. PMID:12914674