Charybdotoxin and noxiustoxin, two homologous peptide inhibitors of the K+(Ca2+) channel

FEBS Letters

Martin, Brian M.¹  Possani, Lourival D.²  Smith, Jeffrey S.²  Valdivia, Hector H.²  Coronado, Roberto² 

[1] National Institute of Mental Health, Molecular Neurogenetics Unit, Clinical Neuroscience Branch, Building 10 3D16, NIH, Bethesda, MD 20892, USA;Department of Physiology and Molecular Biophysics, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX 77030, USA

关键词: Noxiustoxin;    Charybdotoxin;    Amino acid sequence;    K+ channel;    Single-channel recording;    (Skeletal muscle);    CTX;    charybdotoxin;    CM-cellulose;    carboxymethylcellulose;    K+(Ca2+) channels;    Ca2+-activated K+ channels;    NTX;    noxiustoxin;   

DOI  :  10.1016/0014-5793(88)81439-X

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

We show that noxiustoxin (NTX), like charybdotoxin (CTX) described by others, affects Ca²⁺-activated K⁺ channels of skeletal muscle (K⁺(Ca²⁺) channels). Chemical characterization of CTX shows that it is similar to NTX. Although the amino-terminal amino acid of CTX is not readily available, the molecule was partially sequenced after CNBr cleavage. A decapeptide corresponding to the C-terminal region of NTX shows 60% homology to that of CTX, maintaining the cysteine residues at the same positions. While CTX blocks the K⁺(Ca²⁺) channels with a K _d of 1–3 nM, for NTX it is approx. 450 nM. Both peptides can interact simultaneously with the same channel. NTX and CTX promise to be good tools for channel isolation.

【 授权许可】

Unknown