EpI (P00405) Protein Card

General Information
Name EpI
Alternative name(s) EpI-NH2
Organism Conus episcopatus
Organism region Indo-Pacific
Organism diet molluscivorous
Protein Type Wild type
Protein precursor EpI precursor (2925)
Notes Did not inhibit α3β4, α3β2, α3α5β2 or α3α5β4 nAChRs (Nicke, 2003).

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

Modified residues
17nh2C-term amidation
Sequence evidence protein level
Average Mass 1866.00
Monoisotopic Mass 1864.53
Isoelectric Point 4.50
Extinction Coefficient [280nm] 1490.00


IC50: Nicotinic acetylcholine receptors

α3β4H. sapiens64.57 nM[57.54-72.44]30 uM nicotineHo,T.N.T. et al. (2021)
α7R. norvegicus30 nM1.1 100 uM nicotineNicke,A. et al. (2003)
α7-5HT3 chimaeraG. gallus(Expressed in TRex-293 cells. )103 nM 1.43 uM nicotineNicke,A. et al. (2003)

Ki: Nicotinic acetylcholine receptors

AChBPA. californica4.17 nM[3.09-5.89]1 nM [3H]-epibatidineHo,T.N.T. et al. (2021)
L. stagnalis>100 uM1 nM [3H]-epibatidineHo,T.N.T. et al. (2021)

Synthetic variants

Hu,S.H., Loughnan,M., Miller,R., Weeks,C.M., Blessing,R.H., Alewood,P.F., Lewis,R.J. and Martin,J.L. (1998) The 1.1 A resolution crystal structure of [Tyr15]EpI, a novel alpha-conotoxin from Conus episcopatus, solved by direct methods Biochemistry 37:11425-11433
Loughnan,M., Bond,T., Atkins,A., Cuevas,J., Adams,D.J., Broxton,N.M., Livett,B.G., Down,J.G., Jones,A., Alewood,P.F. and Lewis,R.J. (1998) alpha-conotoxin EpI, a novel sulfated peptide from Conus episcopatus that selectively targets neuronal nicotinic acetylcholine receptors J. Biol. Chem. 273:15667-15674
Nicke,A., Samochocki,M., Loughnan,M.L., Bansal,P.S., Maelicke,A. and Lewis,R.J. (2003) Alpha-conotoxins EpI and AuIB switch subtype selectivity and activity in native versus recombinant nicotinic acetylcholine receptors. FEBS Lett. 554:219-223
Ho,T.N.T., Lee,H.S., Swaminathan,S., Goodwin,L., Rai,N., Ushay,B., Lewis,R.J. and Conibear,A.C. (2021) Posttranslational modifications of α-conotoxins: sulfotyrosine and C-terminal amidation stabilise structures and increase acetylcholine receptor binding. RSC Med Chem 12:1574-1584

Internal links
Protein Precursor EpI precursor (2925)
Nucleic acids
Structure EpI

External links
UniProtKB/Swiss-Prot P56638
Ncbi P56638