It is one of a group of short, basic peptides called calcins, which bind to ryanodine receptors (RyRs) and thereby trigger calcium release from the sarcoplasmic reticulum.
The name intrepicalcin is a combination of the species name of the organism that produces it (Vaejovis intrepidus) and the family name of short toxins that it belongs to (calcins).
However, compared to other calcins, intrepicalcin contains two extra positively-charged basic lysines (residue 12 and 14) on its dorsal side.
[2] Imperacalcin, on the other hand, has a matching identity of only 69.7% (ten different residues) and has the lowest similarity with intrepicalcin of all currently known members of the calcin family.
[2] Intrepicalcin exerts its toxic effect by binding to ryanodine receptor 1 (RyR1), which is a calcium release ion channel present in mammalian skeletal muscle cells.
[6] RyR1s can be opened by direct protein-protein interaction with dihydropyridine receptors, which are voltage-sensing L-type calcium channels (CaV1.1).
[6] RyR1 consists of four subunits and has binding sites for several regulatory molecules, such as calcium, calmodulin, ATP and magnesium.
[2] The alterations in the calcium potentials which are caused by intrepicalcin interaction with RyR1, affect these skeletal muscles and result in muscular paralysis.