X-group (possible homology)

5075 Photosystem II antenna protein-like

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Ligands and drugs

1,846

Member domains

1,334

with ligand contacts (≤ 4 Å)

72.3% of members

957

with DrugDomain annotations

51.8% of members

945

with a DrugBank compound

51.2% 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.

107

Proteins with classified ligands

Superclasses bound (of 23)

6.0

Superclasses per 20 proteins

narrower than 75% 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	106	11.8	9.02×	q < 0.0001
Organoheterocyclic compounds	104	16.2	6.41×	q < 0.0001
Homogeneous non-metal compounds	12	22.7	0.53×	q = 0.02
Homogeneous metal compounds	18	51.8	0.35×	q < 0.0001
Organic oxygen compounds	7	21.0	0.33×	q = 6.2e-4
Organic acids and derivatives	3	16.3	0.18×	q = 2.0e-4
Benzenoids	0	7.7	0	q = 1.4e-3
Nucleosides, nucleotides, and analogues	0	29.2	0	q < 0.0001
Hydrocarbons	2	0.7	2.71×	not tested
Organic nitrogen compounds	3	3.4	0.89×	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
DB02133	CLA	Chlorophyll A	856
DB06755	BCR	Beta carotene	835
DB02043	LHG	1,2-Dipalmitoyl-Phosphatidyl-Glycerole	717
DB03426	DGD	Digalactosyl Diacyl Glycerol (Dgdg)	525
DB01022	PQN	Phylloquinone	327
DB04450	HTG	Heptyl 1-Thiohexopyranoside	113
DB03317	HEC	Ferroheme C	107
DB03193	STE	Stearic acid	100
DB03279	LMU	Dodecyl-Alpha-D-Maltoside	84
DB18267	HEM	Ferroheme	73
DB15914	RRX	Cryptoxanthin	50
DB04506	CHL	Chlorophyll B	16
DB00137	LUT	(3R,3'R,6S)-4,5-DIDEHYDRO-5,6-DIHYDRO-BETA,BETA-CAROTENE-3,3'-DIOL	14
DB04735	MGE	Monogalactosyldiacylglycerol	13
DB01853	BCL	Bacteriochlorophyll A	10
DB02379	BGC	Beta-D-Glucose	6
DB12148	1L3	Menatetrenone	6
DB00132	LNL	alpha-Linolenic acid	4
DB00163	VIV	Vitamin E	2
DB01707	LAP	L-Alfa-Lysophosphatidylcholine, Lauroyl	2

Most frequently bound compounds

PDB ligand	Name	Domains in contact
CLA	CHLOROPHYLL A	1,275
BCR	BETA-CAROTENE	1,201
LHG	1,2-DIPALMITOYL-PHOSPHATIDYL-GLYCEROLE	1,074
LMG	1,2-DISTEAROYL-MONOGALACTOSYL-DIGLYCERIDE	878
DGD	DIGALACTOSYL DIACYL GLYCEROL (DGDG)	744
SQD	1,2-DI-O-ACYL-3-O-[6-DEOXY-6-SULFO-ALPHA-D-GLUCOPYRANOSYL]-SN-GLYCEROL	727
OEX	CA-MN4-O5 CLUSTER	264
CL	CHLORIDE ION	248
PQN	PHYLLOQUINONE	237
UNL	Unknown ligand	235
HTG	heptyl 1-thio-beta-D-glucopyranoside	170
CAmetal	CALCIUM ION	115
LMU	DODECYL-ALPHA-D-MALTOSIDE	108
STE	STEARIC ACID	107
OEY	CA-MN4-O6 CLUSTER	54
CL7	CHLOROPHYLL D	44
CHL	CHLOROPHYLL B	41
8CT	(6'R,11cis,11'cis,13cis,15cis)-4',5'-didehydro-5',6'-dihydro-beta,beta-carotene	38
HEM	PROTOPORPHYRIN IX CONTAINING FE	35
HEC	HEME C	33