The name of this superfamily has been modified since the most recent official CATH+ release (v4_3_0). At the point of the last release, this superfamily was named:

Sbi, C3 binding domain IV

Functional Families

Overview of the Structural Clusters (SC) and Functional Families within this CATH Superfamily. Clusters with a representative structure are represented by a filled circle.

Superfamily: Sbi, C3 binding domain IV

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.


GO Diversity

Unique GO annotations
2 Unique GO terms

EC Diversity

Unique EC annotations
0 Unique EC terms

Species Diversity

Unique species annotations
132 Unique species

Sequence/Structure Diversity

Overview of the sequence / structure diversity of this superfamily compared to other superfamilies in CATH. Click on the chart to view the data in more detail.

Superfamily Summary

A general summary of information for this superfamily.
Domains: 16
Domain clusters (>95% seq id): 3
Domain clusters (>35% seq id): 2
Unique PDBs: 9
Structural Clusters (5A): 1
Structural Clusters (9A): 1
FunFam Clusters: 1
Unique EC:
Unique GO: 2
Unique Species: 132