X-group (possible homology)

9 Lipocalins/Streptavidin

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Ligands and drugs

5,955

Member domains

2,880

with ligand contacts (≤ 4 Å)

48.4% of members

2,642

with DrugDomain annotations

44.4% of members

1,899

with a DrugBank compound

31.9% 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.

195

Proteins with classified ligands

Superclasses bound (of 23)

9.3

Superclasses per 20 proteins

broader than 86% 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
Lipids and lipid-like molecules	90	21.4	4.20×	q < 0.0001
Organic nitrogen compounds	15	6.1	2.45×	q = 3.2e-3
Benzenoids	31	14.1	2.21×	q = 1.2e-4
Organoheterocyclic compounds	51	29.6	1.72×	q = 2.4e-4
Homogeneous non-metal compounds	51	41.4	1.23×	q = 0.14
Organic oxygen compounds	35	38.3	0.91×	q = 0.67
Homogeneous metal compounds	68	94.4	0.72×	q = 5.1e-4
Organic acids and derivatives	19	29.8	0.64×	q = 0.06
Nucleosides, nucleotides, and analogues	1	53.2	0.02×	q < 0.0001
Hydrocarbon derivatives	1	0.2	6.05×	not tested
Hydrocarbons	6	1.3	4.47×	not tested
Organohalogen compounds	2	0.6	3.65×	not tested
Phenylpropanoids and polyketides	5	4.0	1.25×	not tested
Organosulfur compounds	4	4.0	1.01×	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
DB00121	BTN	Biotin	237
DB00141	NAG	N-Acetylglucosamine	109
DB03796	PLM	Palmitic Acid	104
DB18267	HEM	Ferroheme	80
DB00162	RTL	Vitamin A	37
DB08231	MYR	Myristic acid	23
DB03549	BNI	Biotinyl P-Nitroaniline	20
DB01672	DBH	2,3-Dihydroxy-Benzoic Acid	18
DB02210	HEZ	Hexane-1,6-Diol	16
DB03353	IMI	2-Iminobiotin	16
DB05381	HSM	Histamine	16
DB02659	CHD	Cholic Acid	14
DB00755	REA	Tretinoin	12
DB04801	VCA	cis-Vaccenic acid	12
DB02710	DBS	2,3,-Dihydroxybenzoylserine	11
DB03017	DAO	Lauric acid	10
DB14104	EIC	Linoleic acid	10
DB04257	PAM	Palmitoleic Acid	9
DB04512	PRZ	2-Isobutyl-3-methoxypyrazine	8
DB04650	BTQ	5-[(3AS,4R,6AR)-2-OXOHEXAHYDRO-1H-THIENO[3,4-D]IMIDAZOL-4-YL]PENTANOIC ACID	8

Most frequently bound compounds

PDB ligand	Name	Domains in contact
BTN	BIOTIN	249
CL	CHLORIDE ION	211
RET	RETINAL	124
PLM	PALMITIC ACID	103
NAG	2-acetamido-2-deoxy-beta-D-glucopyranose	97
HEM	PROTOPORPHYRIN IX CONTAINING FE	85
NAmetal	SODIUM ION	81
ZNmetal	ZINC ION	60
P6G	HEXAETHYLENE GLYCOL	47
RTL	RETINOL	36
FEmetal	FE (III) ION	33
CAmetal	CALCIUM ION	32
CDmetal	CADMIUM ION	31
OLA	OLEIC ACID	29
4OL	N,N'-butane-1,4-diylbis[1-hydroxy-N-(3-{[(1-hydroxy-6-oxo-1,6-dihydropyridin-2-yl)carbonyl]amino}propyl)-6-oxo-1,6-dihydropyridine-2-carboxamide]	27
SCN	THIOCYANATE ION	27
MYR	MYRISTIC ACID	23
UNL	Unknown ligand	23
BNI	5-(2-OXO-HEXAHYDRO-THIENO[3,4-D]IMIDAZOL-6-YL)-PENTANOIC ACID (4-NITRO-PHENYL)-AMIDE	20
KM3	{N-(4-{bis[(pyridin-2-yl-kappaN)methyl]amino-kappaN}butyl)-5-[(3aS,4S,6aR)-2-oxohexahydro-1H-thieno[3,4-d]imidazol-4-yl]pentanamide}iron(3+)	20