Cardiotoxin Analog (CTX) IV 6-12 is a peptide fragment of cyclophosphamide analog (CTX) IV, derived from the venom of Naja atra, and is a unique cardiotoxin analog[1]. Cardiotoxin Analog (CTX) IV 6-12 has a three-finger ring structure similar to neurotoxins and muscarinic toxins and has cytolytic effects on many cells[2]. Cardiotoxin Analog (CTX) IV 6-12 can cause depolarization and contraction of smooth and skeletal muscles, as well as depolarization of nerve cells[3]. Cardiotoxin Analog (CTX) IV 6-12 is able to induce membrane fusion of vesicles formed by phospholipids such as cardiolipin or sphingomyelin[4]. Cardiotoxin Analog (CTX) IV 6-12 is the only cardiotoxin isoform known to date that has a positively charged residue at the N-terminal amino acid[5]. CTX IV differs from CTX II only by the presence of arginine in place of a leucine residue at position 1[6].
References:
[1] Kaneda N, Sasaki T, Hayashi K. Primary structures of cardiotoxin analogues II and IV from the venom of Naja naja atra[J]. Biochimica et Biophysica Acta (BBA)-Protein Structure, 1977, 491(1): 53-66.
[2] Wu W G. Diversity of cobra cardiotoxin[J]. Journal of Toxicology: Toxin Reviews, 1997, 16(3): 115-134.
[3] Harvey A L. Cardiotoxins from cobra venoms: possible mechanisms of action[J]. Journal of Toxicology: Toxin Reviews, 1985, 4(1): 41-69.
[4] Forouhar F, Huang W N, Liu J H, et al. Structural basis of membrane-induced cardiotoxin A3 oligomerization[J]. Journal of Biological Chemistry, 2003, 278(24): 21980-21988.
[5] Jang J Y, Kumar T K S, Jayaraman G, et al. Comparison of the hemolytic activity and solution structures of two snake venom cardiotoxin analogues which only differ in their N-terminal amino acid[J]. Biochemistry, 1997, 36(48): 14635-14641.
[6] Kumar T K S, Pandian S T K, Jayaraman G, et al. Understanding the structure, function and folding of cobra toxins[J]. PROCEEDINGS-NATIONAL SCIENCE COUNCIL REPUBLIC OF CHINA PART A PHYSICAL SCIENCE AND ENGINEERING, 1999, 23: 1-19.