Glucan-binding protein C/Surface antigen I/II, V-domain (IPR013574)

Short name: Glucan-bd_C/Surface_Ag-I/II_V

Overlapping homologous superfamilies

Domain relationships



This domain is found in glucan-binding protein C (GbpC) and in the V-region of surface protein antigen; both these proteins belong to the Spa family of Streptococcal proteins [PMID: 9009329]. This domain consists of a beta-supersandwich of 18 beta-strands in two sheets.

There are at least four types of glucan-binding proteins (Gbp) in Streptococcus mutans, GbpA, GbpB, GbpC and GbpD. These proteins promote the adhesion of Streptococcal bacteria to teeth and are associated with dental caries [PMID: 17241168]. GbpC is a cell-wall anchoring protein that plays an important role in sucrose-dependent adhesion by binding to soluble glucan synthesised by glucosyltransferase D (GTFD) [PMID: 16390340].

Spa antigens I/II are multi-functional proteins expressed at the cell wall surface of oral Streptococci, where they function as adhesins. Antigens I/II recognise a wide range of ligands. They exert an immunomodulatory effect on human cells and are important in inflammatory disorders, such as dental caries. These proteins can be divided into seven regions: signal peptide, N-terminal, A-region (alanine-rich), V-region (variable domain), P-region (proline-rich), C-terminal domain, and a cell wall anchor motif. The V-region is the central domain and exhibits the greatest variability in sequence, and is responsible for binding monocyte receptors, its binding stimulating the release of TNF-alpha from the monocytes. The crystal structure of the V-region revealed a lectin-like fold that displays a putative preformed carbohydrate-binding site stabilised by a metal ion [PMID: 12054777].

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.