9OFS: Immunoglobulin heavy constant alpha 2

Crystal structure of the human IGA2m2 FC fragment-FC-alpha receptor (CD89) complex. Determined by X-ray diffraction at 1.95 Å resolution. Released 13 May 2026.

Method: X-ray diffraction
Resolution: 1.95 Å
Organism: Homo sapiens
Chains: 2
Atoms: 3,443
Mol. weight: 48.57 kDa
Ligands: NAG
Released: 13 May 2026

Explore 9OFS in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9OFS contains 15 α-helices and 39 β-strands across 2 chains. 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: 12 helices, 19 β-strands

Element	Residues	Length	Sheet
β-strand	245-249	5	1
α-helix	250-252	3
α-helix	253-258	6
β-strand	263-271	9	1
β-strand	278-281	4	2
β-strand	290-291	2	1
α-helix	292-294	3
β-strand	295-296	2	1
β-strand	302-309	8	1
α-helix	312-316	5
β-strand	321-326	6	2
α-helix	333	1
β-strand	334-338	5	2
β-strand	345	1	3
α-helix	346-347	2
β-strand	348-352	5	4
α-helix	353-355	3
α-helix	356-361	6
β-strand	364-374	11	4
β-strand	375	1	3
β-strand	380-385	6	5
β-strand	388-389	2	5
α-helix	390-391	2
α-helix	392-394	3
β-strand	396-397	2	4
β-strand	401-402	2	4
α-helix	403-404	2
β-strand	411-420	10	4
α-helix	421-426	6
β-strand	430-435	6	5
β-strand	443-448	6	5

Chain C: 3 helices, 20 β-strands

Element	Residues	Length	Sheet
α-helix	7-9	3
β-strand	10-12	3	6
β-strand	17-19	3	7
β-strand	24-28	5	6
β-strand	36-43	8	8
β-strand	46-54	9	8
β-strand	63-66	4	6
α-helix	71-73	3
β-strand	75-83	9	8
β-strand	87-90	4	8
β-strand	94-96	3	8
β-strand	97-99	3	7
β-strand	106-109	4	9
β-strand	114-115	2	10
β-strand	122-126	5	9
β-strand	134-139	6	7
β-strand	149-150	2	7
β-strand	155-158	4	9
α-helix	164-166	3
β-strand	168-175	8	7
β-strand	182-183	2	7
β-strand	190-192	3	7
β-strand	193-194	2	10

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Immunoglobulin heavy constant alpha 2	A	protein	214	Homo sapiens	P01877 (AlphaFold model)
Immunoglobulin alpha Fc receptor	C	protein	207	Homo sapiens	P24071 (AlphaFold model)

Sequence of entity 1 (A), FASTA

>9OFS_1 Immunoglobulin heavy constant alpha 2 (chains A)
CCHPRLSLHRPALEDLLLGSEANLTCTLTGLRDASGATFTWTPSSGKSAVQGPPERDLCG
CYSVSSVLPGCAQPWNHGETFTCTAAHPELKTPLTANITKSGNTFRPEVHLLPPPSEELA
LNELVTLTCLARGFSPKDVLVRWLQGSQELPREKYLTWASRQEPSQGTTTYAVTSILRVA
AEDWKKGETFSCMVGHEALPLAFTQKTIDRLAGK

Sequence of entity 2 (C), FASTA

>9OFS_2 Immunoglobulin alpha Fc receptor (chains C)
QEGDFPMPFISAKSSPVIPLDGSVKIQCQAIREAYLTQLMIIKNSTYREIGRRLKFWNET
DPEFVIDHMDANKAGRYQCQYRIGHYRFRYSDTLELVVTGLYGKPFLSADRGLVLMPGEN
ISLTCSSAHIPFDRFSLAKEGELSLPQHQSGEHPANFSLGPVDLNVSGIYRCYGWYNRSP
YLWSFPSNALELVVTAIDGRAHHHHHH

Ligands and cofactors

ID	Name	Formula	Copies
NAG	2-acetamido-2-deoxy-beta-D-glucopyranose	C8 H15 N O6	4

Water and common crystallization additives (CL) are not listed.

Primary citation

CRYSTAL STRUCTURE OF HUMAN the IGA2m2 FC FRAGMENT-FC-alpha RECEPTOR (CD89) COMPLEX. Chandravanshi, M., Korzeniowski, M., Tolbert, W.D. et al. To be published.

Other PDB entries of the same protein (UniProt P01877 (AlphaFold model), which also has an AlphaFold model), best resolution first:

6UE9 2.9 Å, Structure of tetrameric sIgA complex (Class 2)
6UE8 3.0 Å, Structure of tetrameric sIgA complex (Class 1)
6UEA 3.0 Å, Structure of pentameric sIgA complex
3CM9 Solution Structure of Human SIgA2

Browse structure collections

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