In:
European Journal of Biochemistry, Wiley, Vol. 254, No. 3 ( 1998-06-15), p. 468-479
Abstract:
Potassium‐channel‐blocking scorpion toxins (α‐K‐toxins) have been shown to be valuable tools for the study of potassium channels. Here we report two toxins, cobatoxin 1 and 2, of 32 amino acids, containing three disulphide bridges, that were isolated from the venom of the Mexican scorpion Centruroides noxius . Their primary sequences show less than 40 % identity to other α‐K‐toxins. It is therefore proposed that they belong to subfamily 9. The cDNA of cobatoxin 1 encodes a putative signal peptide, a putative short propeptide, the mature peptide and two amino acids that are processed to leave cobatoxin 1 amidated at the C‐terminus. In rat brain synaptosomal membranes cobatoxin 1 and cobatoxin 2 bind to a common binding site of α‐K‐toxins with K i values of 109 pM and 87 pM, respectively. Moreover, they block the Shaker and K V 1.1 K + channels with moderate affinities, with K d values of around 0.7 μM and 4.1 μM (Shaker) and 0.5 μM and 1.0 μM (K V 1.1), respectively. A three‐dimensional model of cobatoxin 1 was generated and used to interpret the obtained functional data on a structural basis.
Type of Medium:
Online Resource
ISSN:
0014-2956
,
1432-1033
DOI:
10.1046/j.1432-1327.1998.2540468.x
Language:
English
Publisher:
Wiley
Publication Date:
1998
detail.hit.zdb_id:
1398347-7
detail.hit.zdb_id:
2172518-4
SSG:
12
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