Conserved Site

Conotoxin-I, conserved site (IPR013141)

Short name: Conotoxin-I_CS


Cone snail toxins, conotoxins, are small peptides with disulphide connectivity, that target ion-channels or G-protein coupled receptors. Based on the number and pattern of disulphide bonds and biological activities, conotoxins can be classified into several families [PMID: 11478951]. Omega, delta and kappa families of conotoxins have a knottin or inhibitor cystine knot scaffold. The knottin scaffold is a very special disulphide through disulphide knot, in which the III-VI disulphide bond crosses the macrocycle formed by two other disulphide bonds (I-IV and II-V) and the interconnecting backbone segments, where I-VI indicates the six cysteine residues starting from the N terminus; for further information see the KNOTTIN database (

Conotoxins represent a unique arsenal of neuropharmacologically active peptides that have been evolutionarily tailored to afford unprecedented and exquisite selectivity for a wide variety of ion-channel subtypes. The toxins derived from cone snails are currently being investigated for the treatment of chronic pain, epilepsy, cardiovascular diseases, psychiatric and movement disorders, spasticity, cancer, stroke as well as an anesthetic agent. Several potential analgesic and anti-inflammatory peptides from conotoxin families have been identified and patented [PMID: 10903392, PMID: 15225557], e.g. Conus magus (Magus cone) (Magician's cone snail) omega-conotoxin MVIIa (Ziconotide), which is used for the treatment of chronic pain, Conus catus (Cat cone) omega-conotoxin CVID, which is tested for treating severe morphine-resistant pain stress, and Conus geographus (Geography cone) (Nubecula geographus) omega-conotoxin GVIA, which may exert antagonistic effects against beta-endorphin induced anti-nociception.

The disulphide bonding network as well as specific amino acids in inter-cysteine loops provide specificity of conotoxins [PMID: 10988292]. The cysteine arrangement [C-C-CC-C-C] is the same for omega and delta families, which belong to the O-superfamily. The omega conotoxins are calcium channel blockers, whereas delta conotoxins delay the inactivation of sodium channels [PMID: 11478951]. The M-superfamily Mu conotoxins have two types of cysteine arrangement [CC-C-C-CC] and [CC-C-C-C-C], but knottin scaffold is not observed. Mu conotoxins target the voltage-gated sodium channels [PMID: 11478951] and are useful probes for investigating voltage-dependent sodium channels of excitable tissues [PMID: 2410412]. Alpha conotoxins belong to the A-superfamily and have two types of cysteine arrangement [CC-C-C] and [CCC-C-C-C] [PMID: 1390774]. Alpha conotoxins are competitive nicotinic acetylcholine receptor antagonists. The I-superfamily of conotoxins is characterised by a pattern of eight cysteine residues that form four disulphide bridges. The arrangement of cysteine residues is similar to the Janus-faced atracotoxin peptides characterised from spider venoms [PMID: 12694387, PMID: 15450929].

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE patterns