OmIA (P00006) Protein Card

General Information

Name	OmIA
Alternative name(s)	Om1a
Organism	Conus omaria
Organism region	Indo-Pacific
Organism diet	molluscivorous
Protein Type	Wild type

Classification

Conopeptide class	conotoxin
Gene superfamily	A superfamily
Cysteine framework	I
Pharmacological family	alpha conotoxin

Sequence

GCCSHPACNVNNPHICG(nh2)

Modified residues

position	symbol	name
18	nh2	C-term amidation

Sequence evidence

protein level

Average Mass

1720.93

Monoisotopic Mass

1719.65

Isoelectric Point

8.42

Extinction Coefficient [280nm]

Activity

IC50: Nicotinic acetylcholine receptors

Target	Organism		IC50		n_hill	Agonist	Ref
α1β1δε	M. musculus		>10uM			10uM Ach	Talley,T.T. et al. (2006)
α2β2	R. norvegicus		>10uM			100uM Ach	Talley,T.T. et al. (2006)
α3β2	R. norvegicus		11.0nM	+/-6		100nM Ach	Talley,T.T. et al. (2006)
α3β4	H. sapiens		0.16 uM	+/-0.03		30 uM choline	Ho,T.N.T. et al. (2021)
	R. norvegicus		>10uM			100nM Ach	Talley,T.T. et al. (2006)
α4β2	R. norvegicus		>10uM			100nM Ach	Talley,T.T. et al. (2006)
α6/α3β2	R. norvegicus		201nM	+/-100		100nM Ach	Talley,T.T. et al. (2006)
α7	H. sapiens		290 nM	[240-340]	1.2	200uM Ach	Yu et al. (2018)
		(TQS (10 uM))	0.50 uM	+/-0.09		30 uM choline	Ho,T.N.T. et al. (2021)
		(PNU120596 (10 uM))	0.27 uM	+/-0.02		30uM choline	Ho,T.N.T. et al. (2021)
	R. norvegicus		59 nM	[51-69]	1.2	200uM Ach	Yu et al. (2018)
			27.1nM	+/-12		200uM Ach	Talley,T.T. et al. (2006)

Ki: Nicotinic acetylcholine receptors

Target	Organism	Ki		Competitor	Agonist	Ref
AChBP	L. stagnalis	0.28 uM	+/-0.07	[³H]-epibatidine (1nM)		Ho,T.N.T. et al. (2021)

Synthetic variants

OmIA[H5R]	GCCSRPACNVNNPHICG(nh2)
OmIA[N11D]	GCCSHPACNVDNPHICG(nh2)
OmIA[N9H]	GCCSHPACHVNNPHICG(nh2)
OmIA[V10Q]	GCCSHPACNQNNPHICG(nh2)

References

Talley,T.T., Olivera,B.M., Han,K.H., Christensen,S.B., Dowell,C., Tsigelny,I., Ho,K.Y., Taylor,P. and McIntosh,J.M. (2006) Alpha-conotoxin OmIA is a potent ligand for the acetylcholine-binding protein as well as alpha3beta2 and alpha7 nicotinic acetylcholine receptors J. Biol. Chem. 281:24678-24686

Chi,S.W., Kim,D.H., Olivera,B.M., McIntosh,J.M. and Han,K.H. (2006) Solution conformation of a neuronal nicotinic acetylcholine receptor antagonist alpha-conotoxin OmIA that discriminates alpha3 vs. alpha6 nAChR subtypes Biochem. Biophys. Res. Commun. 345:248-254

Yu, J., Zhu, X., Zhang, L., Kudryavtsev, D., Kasheverov, I., Lei, Y., Zhangsun, D., Tsetlin, V. and Luo, S. (2018) Species specificity of rat and human α7 nicotinic acetylcholine receptors towards different classes of peptide and protein antagonists Neuropharmacology 139:226-237

Ho,T.N.T., Abraham,N., Lewis,R.J. (2021) Unique Pharmacological Properties of α-Conotoxin OmIA at α7 nAChRs. Front Pharmacol 12:803397

Internal links

Nucleic acids
Structure	SOLUTION STRUCTURE OF ALPHA-CONOTOXIN OMIA Alpha-conotoxin OmIA with unusual pharmacological properties at alpha7 nicotinic receptors

External links

UniProtKB/Swiss-Prot	P0C1R7
Ncbi	2GCZ_A, P0C1R7

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