X-group (possible homology)

390 Hairpin loop containing domain-like

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Ligands and drugs

1,556

Member domains

158

with ligand contacts (≤ 4 Å)

10.2% of members

146

with DrugDomain annotations

9.4% of members

132

with a DrugBank compound

8.5% 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.

Proteins with classified ligands

Superclasses bound (of 23)

—

Superclasses per 20 proteins

fewer than 20 proteins: too few to compare at equal depth

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
Homogeneous metal compounds	2	7.7	0.26×	q = 9.2e-3
Organic oxygen compounds	10	3.1	3.18×	not tested
Mixed metal/non-metal compounds	1	0.3	3.02×	not tested
Homogeneous non-metal compounds	7	3.4	2.06×	not tested
Organic acids and derivatives	2	2.4	0.82×	not tested
Organoheterocyclic compounds	1	2.4	0.41×	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	49
DB14533	—	—	6
DB12831	—	—	5
DB01593	—	—	4
DB14487	—	—	4
DB02580	PG6	Pentaglyme	3
DB04161	ROP	Propionamide	3
DB00133	SER	Serine	2
DB03959	SGN	N,O6-Disulfo-Glucosamine	2
DB11326	BO3	Boric acid	2
DB00145	GLY	Glycine	1
DB03567	A2G	alpha-N-Acetyl-D-galactosamine	1
DB08217	MTN	S-[(1-Hydroxy-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-3-yl)methyl] methanesulfonothioate	1
DB09130	—	—	1

Most frequently bound compounds

PDB ligand	Name	Domains in contact
NAG	2-acetamido-2-deoxy-beta-D-glucopyranose	55
CL	CHLORIDE ION	32
YIO	1-thio-beta-D-galactopyranose	8
BO3	BORIC ACID	3
ROP	PROPIONAMIDE	3
COmetal	COBALT (II) ION	2
MRD	(4R)-2-METHYLPENTANE-2,4-DIOL	2
NAmetal	SODIUM ION	2
PG6	1-(2-METHOXY-ETHOXY)-2-{2-[2-(2-METHOXY-ETHOXY]-ETHOXY}-ETHANE	2
A2G	2-acetamido-2-deoxy-alpha-D-galactopyranose	1
CAmetal	CALCIUM ION	1
CDmetal	CADMIUM ION	1
GLY	GLYCINE	1
MTN	S-[(1-oxyl-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-3-yl)methyl] methanesulfonothioate	1
SGN	2-deoxy-6-O-sulfo-2-(sulfoamino)-alpha-D-glucopyranose	1