1QQF

N-TERMINALLY TRUNCATED C3D,G FRAGMENT OF THE COMPLEMENT SYSTEM

Summary for 1QQF

• Entry DOI: 10.2210/pdb1qqf/pdb
• Descriptor: PROTEIN (COMPLEMENT C3DG) (2 entities in total)
• Functional Keywords: alpha-alpha barrel, complement, immune system
• Biological source: Rattus norvegicus (Norway rat)
• Cellular location: Secreted: P01026
• Total number of polymer chains: 1
• Total formula weight: 31167.40

Authors

Zanotti, G.,Bassetto, A.,Battistutta, R.,Stoppini, M.,Berni, R. (deposition date: 1999-06-04, release date: 2000-07-31, Last modification date: 2024-10-16)

Primary citation

Zanotti, G.,Bassetto, A.,Battistutta, R.,Folli, C.,Arcidiaco, P.,Stoppini, M.,Berni, R.
Structure at 1.44 A resolution of an N-terminally truncated form of the rat serum complement C3d fragment.
Biochim.Biophys.Acta, 1478:232-238, 2000

PubMed Abstract: Complement component C3 plays a key role in the complement-mediated immune defence, and occupies a central position within the complement cascade system. One of its degradation products, C3dg, was purified from rat serum and crystallised in two different crystal forms as N-terminally truncated fragment. Despite the truncation and the lack of a significant portion of the N-terminus as compared to C3d, the structure of the fragment is highly similar to that of recombinant human C3d (Nagar et al., Science 280 (1998) 1277-1281). Structural details of the reactive site have been obtained, suggesting a possible mode of thioester bond formation between Cys-1010 and Gln-1013 and thioester bond cleavage in the transacylation reaction involving His-1126. The truncation at the N-terminus of C3d leads to the exposure of a surface of the molecule that favours dimerisation, so that in both crystal forms, the fragment is present as a dimer, with monomers related by a two-fold axis.

PubMed: 10825534
DOI: 10.1016/S0167-4838(00)00040-6

Experimental method

X-RAY DIFFRACTION (1.45 Å)