X-group (possible homology)

108 EF-hand

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Ligands and drugs

16,175

Member domains

3,767

with ligand contacts (≤ 4 Å)

23.3% of members

2,678

with DrugDomain annotations

16.6% of members

889

with a DrugBank compound

5.5% 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.

334

Proteins with classified ligands

Superclasses bound (of 23)

8.0

Superclasses per 20 proteins

broader than 56% 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
Homogeneous metal compounds	293	161.7	1.81×	q < 0.0001
Phenylpropanoids and polyketides	11	6.9	1.61×	q = 0.17
Organosulfur compounds	9	6.8	1.33×	q = 0.41
Benzenoids	28	24.1	1.16×	q = 0.47
Lipids and lipid-like molecules	33	36.7	0.90×	q = 0.68
Homogeneous non-metal compounds	44	70.9	0.62×	q = 5.9e-4
Organic oxygen compounds	32	65.6	0.49×	q < 0.0001
Organoheterocyclic compounds	24	50.7	0.47×	q < 0.0001
Mixed metal/non-metal compounds	3	6.9	0.43×	q = 0.23
Organic acids and derivatives	20	51.0	0.39×	q < 0.0001
Organic nitrogen compounds	3	10.5	0.29×	q = 0.02
Nucleosides, nucleotides, and analogues	4	91.0	0.04×	q < 0.0001
Organohalogen compounds	3	0.9	3.20×	not tested
Alkaloids and derivatives	2	1.1	1.78×	not tested
Hydrocarbons	3	2.3	1.30×	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
DB18267	HEM	Ferroheme	98
DB00141	NAG	N-Acetylglucosamine	83
DB00831	TFP	Trifluoperazine	36
DB11093	—	—	29
DB11348	—	—	29
DB14481	—	—	29
DB02241	CZH	8-Benzyl-2-Hydroperoxy-2-(4-Hydroxy-Benzyl)-6-(4-Hydroxy-Phenyl)-2h-Imidazo[1,2-a]Pyrazin-3-One	26
DB08231	MYR	Myristic acid	18
DB03796	PLM	Palmitic Acid	14
DB01373	—	—	13
DB02055	NBB	N-Butyl-Benzenesulfonamide	13
DB00864	FK5	Tacrolimus	11
DB00433	P77	Prochlorperazine	10
DB04049	CEI	Coelenteramide	10
DB04327	PEE	Phosphatidylethanolamine	8
DB00477	Z80	Chlorpromazine	7
DB00909	—	Zonisamide	7
DB02175	MLA	Malonic acid	7
DB02570	ISA	PD150606	7
DB03345	BME	Mercaptoethanol	7

Most frequently bound compounds

PDB ligand	Name	Domains in contact
CAmetal	CALCIUM ION	2,637
MGmetal	MAGNESIUM ION	234
HEM	PROTOPORPHYRIN IX CONTAINING FE	215
CL	CHLORIDE ION	150
NAmetal	SODIUM ION	148
ZNmetal	ZINC ION	141
NAG	2-acetamido-2-deoxy-beta-D-glucopyranose	114
TFP	10-[3-(4-METHYL-PIPERAZIN-1-YL)-PROPYL]-2-TRIFLUOROMETHYL-10H-PHENOTHIAZINE	36
MNmetal	MANGANESE (II) ION	35
9A3	(2S)-8-benzyl-2-hydroperoxy-6-(4-hydroxyphenyl)-2-{[4-(trifluoromethyl)phenyl]methyl}imidazo[1,2-a]pyrazin-3(2H)-one	32
J2U	(2~{S})-6-(4-hydroxyphenyl)-2-[(4-hydroxyphenyl)methyl]-4-(phenylmethyl)-2,3-dihydroinden-1-one	32
J2X	(2~{S})-2-(hydroxymethyl)-6-(4-hydroxyphenyl)-2-[(4-hydroxyphenyl)methyl]-4-(phenylmethyl)-3~{H}-inden-1-one	32
CZH	C2-HYDROPEROXY-COELENTERAZINE	28
MYR	MYRISTIC ACID	21
NImetal	NICKEL (II) ION	21
CDmetal	CADMIUM ION	20
A1B92	Rimtuzalcap	19
BR	BROMIDE ION	18
SRmetal	STRONTIUM ION	18
MAN	alpha-D-mannopyranose	16