9RO7: Human CD22 Ig domains 1-3

Crystal structure of human CD22 Ig domains 1-3 in complex with modified sialoside 7-012. Determined by X-ray diffraction at 3.15 Å resolution. Released 10 Dec 2025.

Method: X-ray diffraction
Resolution: 3.15 Å
Organism: Homo sapiens
Chains: 4
Atoms: 9,883
Mol. weight: 152.41 kDa
Ligands: A1JJO
Released: 10 Dec 2025

Explore 9RO7 in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9RO7 contains 15 α-helices and 126 β-strands across 4 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: 3 helices, 31 β-strands

Element	Residues	Length	Sheet
β-strand	24-27	4	1
β-strand	31-35	5	2
β-strand	40-42	3	3
β-strand	45-48	4	1
β-strand	55-65	11	2
β-strand	70-78	9	2
β-strand	92-94	3	3
β-strand	101	1	1
β-strand	104-106	3	3
α-helix	111-113	3
β-strand	115-122	8	2
β-strand	127-137	11	2
α-helix	140-142	3
β-strand	144-146	3	4
β-strand	151-152	2	5
β-strand	157-163	7	4
β-strand	167	1	6
β-strand	170	1	6
β-strand	172-178	7	7
β-strand	181-182	2	7
β-strand	187-193	7	4
β-strand	198-206	9	4
α-helix	210-212	3
β-strand	216-223	8	7
β-strand	228-235	8	7
β-strand	238-239	2	5
β-strand	240-249	10	8
β-strand	261-271	11	8
β-strand	274-281	8	9
β-strand	285	1	9
β-strand	293-296	4	8
β-strand	306-313	8	9
β-strand	317-319	3	9
β-strand	323-324	2	9

Chain B: 4 helices, 35 β-strands

Element	Residues	Length	Sheet
β-strand	24-27	4	10
β-strand	31-35	5	11
β-strand	40-42	3	12
β-strand	45-48	4	10
β-strand	55-60	6	11
β-strand	63-65	3	13
β-strand	70-72	3	13
β-strand	75-78	4	11
β-strand	92-94	3	12
β-strand	101	1	10
β-strand	104-106	3	12
α-helix	111-113	3
β-strand	115-122	8	11
β-strand	127-137	11	11
α-helix	140-142	3
β-strand	144-145	2	14
β-strand	151-152	2	15
β-strand	157-163	7	14
β-strand	167	1	16
β-strand	170	1	16
β-strand	173-178	6	17
β-strand	181-182	2	17
β-strand	187-193	7	14
β-strand	198-206	9	14
α-helix	210-212	3
β-strand	216-222	7	17
β-strand	228-235	8	17
β-strand	238-239	2	15
β-strand	240-249	10	18
β-strand	254	1	19
β-strand	261-271	11	18
β-strand	274-281	8	20
β-strand	284-285	2	20
α-helix	286	1
β-strand	293-296	4	18
β-strand	305-313	9	20
β-strand	317-319	3	20
β-strand	323-325	3	20
β-strand	326	1	19

Chain C: 4 helices, 29 β-strands

Element	Residues	Length	Sheet
β-strand	27	1	21
β-strand	31-35	5	22
β-strand	40-42	3	23
β-strand	45	1	21
β-strand	56-60	5	22
β-strand	63-65	3	24
β-strand	70-72	3	24
β-strand	75-78	4	22
β-strand	92-94	3	23
β-strand	104-106	3	23
α-helix	111-113	3
β-strand	115-122	8	22
β-strand	127-137	11	22
α-helix	140-142	3
β-strand	144-146	3	25
β-strand	151-152	2	26
β-strand	157-163	7	25
β-strand	173-178	6	27
β-strand	181-182	2	27
β-strand	187-193	7	25
β-strand	198-206	9	25
α-helix	210-212	3
β-strand	216-222	7	27
β-strand	228-235	8	27
β-strand	238-239	2	26
β-strand	240-248	9	28
β-strand	263-271	9	28
β-strand	276-281	6	29
α-helix	285-286	2
β-strand	293-294	2	28
β-strand	307-312	6	29
β-strand	317-319	3	29
β-strand	323	1	29

Chain D: 4 helices, 31 β-strands

Element	Residues	Length	Sheet
β-strand	25-27	3	30
β-strand	31-35	5	31
β-strand	40-42	3	32
β-strand	45-47	3	30
β-strand	55-65	11	31
β-strand	70-78	9	31
β-strand	92-94	3	32
β-strand	101	1	30
β-strand	104-106	3	32
α-helix	111-113	3
β-strand	115-122	8	31
β-strand	127-137	11	31
α-helix	140-142	3
β-strand	144-146	3	33
β-strand	151-152	2	34
β-strand	157-162	6	33
β-strand	167	1	35
β-strand	170	1	35
β-strand	173-178	6	36
β-strand	182	1	36
β-strand	187-193	7	33
β-strand	198-206	9	33
β-strand	216-222	7	36
β-strand	228-235	8	36
β-strand	238-239	2	34
β-strand	240-249	10	37
β-strand	261-271	11	37
β-strand	274-281	8	38
β-strand	284-285	2	38
α-helix	286	1
β-strand	293-296	4	37
α-helix	301-303	3
β-strand	306-313	8	38
β-strand	317-319	3	38
β-strand	323-324	2	38

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
B-cell receptor CD22	A, B, C, D	protein	324	Homo sapiens	P20273 (AlphaFold model)

Sequence of entity 1 (A, B, C, D), FASTA

>9RO7_1 B-cell receptor CD22 (chains A, B, C, D)
ETGDSSKWVFEHPETLYAWEGACVWIPCTYRALDGDLESFILFHNPEYNKATSKFDGTRL
YESTKDGKVPSEQKRVQFLGDKNKNCTLSIHPVHLADSGQLGLRMESKTEKWMERIHLAV
SERPFPPHIQLPPEIQESQEVTLTCLLAFSCYGYPIQLQWLLEGVPMRQAAVTSTSLTIK
SVFTRSELKFSPQWSHHGKIVTCQLQDADGKFLSADTVQLNVKHTPKLEIKVTPSDAIVR
EGDSVTMTCEVSSSNPEYTTVSWLKDGTSLKKQNTFTLNLREVTKDQSGKYCCQVSNDVG
PGRSEEVFLQVQYAGGTKHHHHHH

Ligands and cofactors

ID	Name	Formula	Copies
A1JJO	(2R,4S,5R,6R)-5-acetamido-6-[(1S,2S)-1,2-bis(oxidanyl)-3-[(4-phenylphenyl)carbo…	C34 H40 N8 O11	4

Water and common crystallization additives (SO4) are not listed.

Primary citation

Molecular Insights into the Engagement of High-Affinity Sialylated Ligands to Human CD22. Ereno-Orbea, J., Pang, L., Sicard, T. et al. JACS Au (2025) 5:5524-5537. DOI 10.1021/jacsau.5c01013 · PubMed

Other PDB entries of the same protein (UniProt P20273 (AlphaFold model), which also has an AlphaFold model), best resolution first:

5VKJ 2.12 Å, Crystal structure of human CD22 Ig domains 1-3
5VKM 2.2 Å, Crystal structure of human CD22 Ig domains 1-3 in complex with alpha 2-6 sialyllactose
7O52 2.41 Å, CD22 d6-d7 in complex with Fab m971
9ROB 2.7 Å, Crystal structure of human CD22 Ig domains 1-3 in complex with modified sialoside 1B
9RM3 2.86 Å, Crystal structure of human CD22 Ig domains 1-3 in complex with modified sialoside 17
5VL3 3.1 Å, CD22 d1-d3 in complex with therapeutic Fab Epratuzumab

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