This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.
Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.
1hp2
From Proteopedia
| |||||||
| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
SOLUTION STRUCTURE OF A TOXIN FROM THE SCORPION TITYUS SERRULATUS (TSTX-K ALPHA) DETERMINED BY NMR.
Overview
A toxin from the scorpion Tityus serrulatus (TsTX-Kalpha) blocks native squid K(+) channels and their cloned counterpart, sqKv1A, at pH 8 ((native)K(d) approximately 20 nM; (sqKv1A)K(d) approximately 10 nM). In both cases, decreasing the pH below 7.0 significantly diminishes the TsTX-Kalpha effect (pK = 6.6). In the cloned squid channel, the pH dependence of the block is abolished by a single point mutation (H351G), and no change in toxin affinity was observed at higher pH values (pH > or =8.0). To further investigate the TsTX-Kalpha-sqKv1A interaction, the three-dimensional structure of TsTX-Kalpha was determined in solution by NMR spectroscopy, and a model of the TsTX-Kalpha-sqKv1A complex was generated. As found for other alpha-K toxins such as charybdotoxin (CTX), site-directed mutagenesis at toxin residue K27 (K27A, K27R, and K27E) significantly reduced the toxin's affinity for sqKv1A channels. This is consistent with the TsTX-Kalpha-sqKv1A model reported here, which has K27 of the toxin inserted into the ion conduction pathway of the K(+) channel. This toxin-channel model also illustrates a possible mechanism for the pH-dependent block whereby lysine residues from TsTX-Kalpha (K6 and K23) are repelled by protonated H351 on sqKv1A at low pH.
About this Structure
1HP2 is a Single protein structure of sequence from Tityus serrulatus. Full crystallographic information is available from OCA.
Reference
Interaction of a toxin from the scorpion Tityus serrulatus with a cloned K+ channel from squid (sqKv1A)., Ellis KC, Tenenholz TC, Jerng H, Hayhurst M, Dudlak CS, Gilly WF, Blaustein MP, Weber DJ, Biochemistry. 2001 May 22;40(20):5942-53. PMID:11352729
Page seeded by OCA on Sun Mar 30 21:08:34 2008
