X-ray crystal structure of C3d

A C3 fragment and ligand for complement receptor 2

Bhushan Nagar, Russell G. Jones, Russell J. Diefenbach, David E. Isenman, James M. Rini*

*Corresponding author for this work

Research output: Contribution to journalArticle

154 Citations (Scopus)


Activation and covalent attachment of complement component C3 to pathogens is the key step in complement-mediated host defense. Additionally, the antigen-bound C3d fragment interacts with complement receptor 2 (CR2; also known as CD21) on B cells and thereby contributes to the initiation of an acquired humoral response. The x-ray crystal structure of human C3d solved at 2.0 angstroms resolution reveals an α-α barrel with the residues responsible for thioester formation and covalent attachment at one end and an acidic pocket at the other. The structure supports a model whereby the transition of native C3 to its functionally active state involves the disruption of a complementary domain interface and provides insight into the basis for the interaction between C3d and CR2.

Original languageEnglish
Pages (from-to)1277-1281
Number of pages5
Issue number5367
Publication statusPublished - 1998
Externally publishedYes

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