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α-Conotoxin EI is an 18-amino-acid peptide originally isolated from Conus ermineus. It has an unusual sequence compared with the classical short α3/5 conotoxins and belongs to the α4/7 structural class. EI acts primarily on nicotinic acetylcholine receptors and has been used to investigate muscle receptor pharmacology, agonist-binding interfaces, and receptor subtype recognition.
A distinguishing structural feature is the presence of hydroxyproline (Hyp) near the N-terminus, together with two native disulfide bonds and C-terminal amidation.
Product Information
| Property | Specification |
|---|---|
| Product Name | α-Conotoxin EI |
| Catalog No. | AS2579 |
| CAS No. | 170663-33-9 |
| Sequence | RD(Hyp)CCYHPTCNMSNPQIC-NH₂ |
| Length | 18 amino acids |
| C-Terminus | Amide |
| Disulfide Connectivity | Cys4–Cys10; Cys5–Cys18 |
| Cysteine Framework | CC–C–C |
| α-Conotoxin Class | α4/7 |
| Natural Source | Conus ermineus |
| Primary Research Target | Muscle-type nAChRs |
| Form | Lyophilized peptide |
The original characterization confirmed the 18-residue sequence, hydroxyproline modification, C-terminal amide, and Cys4–Cys10/Cys5–Cys18 disulfide connectivity.
Distinct nAChR Recognition
EI differs substantially from short muscle-selective α-conotoxins such as GI and MI. Early receptor studies demonstrated that these structural differences translate into distinct recognition of agonist-binding interfaces.
In Torpedo receptors, EI showed preference for the α/δ interface, whereas MI displayed a contrasting preference for the α/γ interface. Mammalian receptor systems show a different balance, illustrating why species and receptor composition need to be reported when interpreting α-Conotoxin EI activity.
Muscle and Neuronal Receptor Studies
Later research has extended EI pharmacology beyond classical muscle receptors. Activity has been examined at neuronal nAChR combinations including α3β4 and α4β2, while muscle-type receptors remain an important experimental target.
This broader profile makes EI useful when researchers want to compare receptor recognition across muscle and neuronal nicotinic subtypes rather than study a single receptor in isolation.
Modified Sequence and Synthetic Design
The mature sequence is:
RD(Hyp)CCYHPTCNMSNPQIC-NH₂
For synthetic EI, hydroxyproline identity, C-terminal amidation, and native disulfide formation should be defined together with the amino-acid sequence.
These characteristics also make EI an informative scaffold for analog development. Projects involving Hyp substitution, loop modification, terminal changes, or receptor-selectivity studies can be evaluated through Custom Peptide Synthesis.
Quality Control and Laboratory Planning
For a post-translationally modified, disulfide-containing peptide, We recommend reviewing molecular identity and expected molecular form in addition to HPLC purity.
Analytical HPLC and MS information can be incorporated into batch documentation according to the selected specification. See Peptide Quality Control for additional information.
Researchers comparing EI with other receptor and ion-channel probes can browse Bioactive Toxin-Derived Peptides.
Storage and Handling
Store lyophilized α-Conotoxin EI according to the conditions provided for the supplied batch. After reconstitution, solvent, concentration, pH, temperature, and storage duration should be considered when establishing working conditions.
Research Use Only
α-Conotoxin EI is supplied for research use only. It is not intended for therapeutic, or human use.