X-group (possible homology)

3847 Hemagglutinin HA2 chain

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Ligands and drugs

1,317

Member domains

675

with ligand contacts (≤ 4 Å)

51.3% of members

634

with DrugDomain annotations

48.1% of members

592

with a DrugBank compound

45.0% of members

Aggregated over all current member domains of this group. Drug annotations come from DrugDomain; buffers and crystallization additives are excluded from the tables below.

Chemical profile

ClassyFire chemical superclasses of the ligands bound by this X-group's proteins, from DrugDomain annotations.

100

Proteins with classified ligands

Superclasses bound (of 23)

4.0

Superclasses per 20 proteins

narrower than 89% of the 256 X-groups with enough proteins to compare (median 7.6)

The raw number of superclasses rises with the number of proteins sampled; the per-20 value compares X-groups at equal depth.

Superclass	Proteins	Expected	Ratio	Significance
Organic oxygen compounds	94	19.6	4.79×	q < 0.0001
Organoheterocyclic compounds	6	15.2	0.40×	q = 0.01
Homogeneous non-metal compounds	4	21.2	0.19×	q < 0.0001
Benzenoids	1	7.2	0.14×	q = 0.02
Homogeneous metal compounds	4	48.4	0.08×	q < 0.0001
Organic acids and derivatives	1	15.3	0.07×	q < 0.0001
Lipids and lipid-like molecules	0	11.0	0	q < 0.0001
Nucleosides, nucleotides, and analogues	0	27.3	0	q < 0.0001
Hydrocarbons	1	0.7	1.45×	not tested
Organic nitrogen compounds	3	3.2	0.95×	not tested

enriched (q < 0.05)depleted (q < 0.05)not significantnot tested (expected < 5)

Unit: a protein (UniProt accession) with a ligand-binding domain in this X-group, counted once per superclass. Expected counts use each superclass's frequency across all ligand-binding X-groups; significance is Fisher's exact test with Benjamini–Hochberg correction. Buffers and crystallization additives are excluded. ECOD v295.2; the method follows the ECOD 2027 update, whose published figures used a slightly different artifact filter.

DrugBank compounds

DrugBank	PDB ligand	Name	Domains
DB00141	NAG	N-Acetylglucosamine	571
DB13609	75U	Umifenovir	9
DB03434	MPO	3-(N-morpholino)propanesulfonic acid	7
DB04237	TAM	Tris(Hydroxyethyl)Aminomethane	7
DB03309	NHE	N-cyclohexyltaurine	3
DB04473	FUC	alpha-L-fucose	3
DB03940	OXM	Oxamic Acid	2
DB03556	PE5	2-(2-{2-[2-(2-{2-[2-(2-Ethoxy-Ethoxy)-Ethoxy]-Ethoxy}-Ethoxy)-Ethoxy]-Ethoxy}-Ethoxy)-Ethanol, Polyethyleneglycol Peg400	1

Most frequently bound compounds

PDB ligand	Name	Domains in contact
NAG	2-acetamido-2-deoxy-beta-D-glucopyranose	565
CAmetal	CALCIUM ION	42
75U	ethyl 6-bromo-4-[(dimethylamino)methyl]-5-hydroxy-1-methyl-2-[(phenylsulfanyl)methyl]-1H-indole-3-carboxylate	9
CL	CHLORIDE ION	8
MPO	3[N-MORPHOLINO]PROPANE SULFONIC ACID	7
IOD	IODIDE ION	6
UPL	UNKNOWN BRANCHED FRAGMENT OF PHOSPHOLIPID	6
TAM	TRIS(HYDROXYETHYL)AMINOMETHANE	5
EYK	2-tert-butylbenzene-1,4-diol	4
FUC	alpha-L-fucopyranose	4
NAmetal	SODIUM ION	3
NHE	2-[N-CYCLOHEXYLAMINO]ETHANE SULFONIC ACID	3
NImetal	NICKEL (II) ION	3
R3P	2,6-dichloro-N-[1-(propan-2-yl)piperidin-4-yl]benzamide	3
EZ7	N-[2-(2-{4-[(R)-(2-methyl-2H-tetrazol-5-yl)(phenyl)methyl]piperazine-1-carbonyl}pyridin-4-yl)-1,3-benzoxazol-5-yl]acetamide	2
MGmetal	MAGNESIUM ION	2
OXM	OXAMIC ACID	2
ETX	2-ETHOXYETHANOL	1
FIE	(S~6~S)-N-{3-chloro-4-[(2S)-2-phenylmorpholine-4-carbonyl]phenyl}-5,7-dihydro-6H-pyrrolo[3,4-b]pyridine-6-sulfonimidoyl fluoride	1
PE5	3,6,9,12,15,18,21,24-OCTAOXAHEXACOSAN-1-OL	1