2I6Q: Complement component C2a

Complement component C2a. Determined by X-ray diffraction at 2.1 Å resolution. Released 17 Oct 2006.

Method: X-ray diffraction
Resolution: 2.1 Å
Organism: Homo sapiens
Chains: 1
Atoms: 4,226
Mol. weight: 60 kDa
Ligands: NAG, MN, MLI
Released: 17 Oct 2006

Explore 2I6Q in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

2I6Q contains 26 α-helices and 28 β-strands across 1 chain. Residue ranges use author residue numbering, as in the PDB file, from PDBe. To see them in 3D, choose the Cartoon representation with Secondary structure coloring: helices, sheets and coils get different colors.

Chain A: 26 helices, 28 β-strands

Element	Residues	Length	Sheet
β-strand	225-226	2	1
β-strand	232-240	9	2
α-helix	247-264	18
α-helix	265-267	3
β-strand	271-278	8	2
β-strand	282-286	5	2
α-helix	291-294	4
α-helix	296-305	10
α-helix	308-311	4
α-helix	319-337	19
α-helix	342-345	4
β-strand	347-354	8	2
α-helix	365-376	12
α-helix	381-385	5
β-strand	386-393	8	2
α-helix	400-406	7
β-strand	410	1	3
β-strand	413	1	3
β-strand	416-419	4	2
α-helix	422-432	11
β-strand	433-434	2	1
α-helix	454-457	4
β-strand	461-465	5	4
β-strand	472-476	5	4
β-strand	481-484	4	4
α-helix	486-488	3
α-helix	495-497	3
β-strand	499-502	4	4
β-strand	511-513	3	4
β-strand	515-520	6	4
α-helix	530-532	3
β-strand	543-547	5	4
β-strand	554	1	5
β-strand	557	1	5
α-helix	559-560	2
β-strand	561	1	6
β-strand	565	1	7
α-helix	566-571	6
α-helix	580-587	8
β-strand	592-598	7	6
β-strand	604-610	7	6
α-helix	613-619	7
α-helix	620-624	5
α-helix	635-637	3
β-strand	643-646	4	6
α-helix	656-658	3
β-strand	662-667	6	6
β-strand	670-680	11	6
α-helix	704-705	2
β-strand	707-711	5	6
α-helix	712-714	3
α-helix	716-723	8
β-strand	729	1	7
α-helix	730-731	2

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Complement C2a fragment	A	protein	517	Homo sapiens	P06681 (AlphaFold model)

Sequence of entity 1 (A), FASTA

>2I6Q_1 Complement C2a fragment (chains A)
HHHHHHGSKIQIQRSGHLNLYLLLDCSQSVSENDFLIFKESASLMVDRIFSFEINVSVAI
ITFASEPKVLMSVLNDNSRDMTEVISSLENANYKDHENGTGTNTYAALNSVYLMMNNQMR
LLGMETMAWQEIRHAIILLTDGKSNMGGSPKTAVDHIREILNINQKRNDYLDIYAIGVGK
LDVDWRELNELGSKKDGERHAFILQDTKALHQVFEHMLDVSKLTDTICGVGNMSANASDQ
ERTPWHVTIKPKSQETCRGALISDQWVLTAAHCFRDGNDHSLWRVNVGDPKSQWGKEFLI
EKAVISPGFDVFAKKNQGILEFYGDDIALLKLAQKVKMSTHARPICLPCTMEANLALRRP
QGSTCRDHENELLNKQSVPAHFVALNGSKLNINLKMGVEWTSCAEVVSQEKTMFPNLTDV
REVVTDQFLCSGTQEDESPCKGESGGAVFLERRFRFFQVGLVSWGLYNPCLGSADKNSRK
RAPRSKVPPPRDFHINLFRMQPWLRQHLGDVLNFLPL

Ligands and cofactors

ID	Name	Formula	Copies
NAG	2-acetamido-2-deoxy-beta-D-glucopyranose	C8 H15 N O6	1
MN	Manganese (II) ion	Mn	1
MLI	Malonate ion	C3 H2 O4	1

Primary citation

Structure of complement component c2a: implications for convertase formation and substrate binding. Milder, F.J., Raaijmakers, H.C., Vandeputte, M.D. et al. Structure (2006) 14:1587-1597. DOI 10.1016/j.str.2006.08.008 · PubMed

Other PDB entries of the same protein (UniProt P06681 (AlphaFold model), which also has an AlphaFold model), best resolution first:

3ERB 1.8 Å, The Crystal Structure of C2b, a Fragment of Complement Component C2 produced during…
8ACF 1.8 Å, Structure of the argX-117 in complex with a complement C2 fragment at low pH
8ACI 1.85 Å, Structure of ARG-117 Fab in complex with a fragment of complement C2, neutral pH
9ZCJ 2.6 Å, Therapeutic antibody with captured antigen
2I6S 2.7 Å, Complement component C2a
9U60 2.9 Å, C3 convertases zymogen C4b2 in loading state
9U5Z 3.1 Å, C3 convertases zymogen C4b2 in activation state
9U61 3.1 Å, CP/MBL pathways C3 convertase C4b2a and C3 complex
9QJ5 3.5 Å, Structure of the Complement classical and lectin pathway proconvertase, C4b2
9QK2 3.5 Å, Structure of the Complement classical and lectin pathway C3 convertase in complex with…
9QJ4 3.9 Å, Structure of the Complement classical and lectin pathway proconvertase, C4b2
9QPY 4.3 Å, Structure of the Complement classical and lectin pathway C3 convertase

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