Homologous Superfamily

Sbi, C3 binding domain IV (IPR041909)

Short name: Sbi_C3_db_domIV

Overlapping entries


This superfamily includes the immunoglobulin-binding protein Sbi domain IV (Sbi-IV) which binds the central complement protein C3. Sbi-IV interacts with Sbi-III to induce a consumption of complement via alternative pathway activation [PMID: 18550524]. When not interacting with Sbi-III, Sbi-IV inhibits the alternative pathway without complement consumption. Sbi-IV structurally comprises a three-helix bundle [PMID: 18550524].

Sbi-IV is similar to Efb-C and Ehp [PMID: 18687868, PMID: 17351618, PMID: 17699522]. Sbi-IV binds to the thioester-containing domain of native C3. The interaction between Sbi-IV and C3, in the presence of domain III, results in the formation of a covalent Sbi-III-IV-C3 adduct followed by futile fluid phase consumption of C3 [PMID: 21055811].

Contributing signatures

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