1v4l
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(New page: 200px<br /><applet load="1v4l" size="450" color="white" frame="true" align="right" spinBox="true" caption="1v4l, resolution 2.8Å" /> '''Crystal structure of ...)
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Revision as of 02:28, 25 November 2007
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Crystal structure of a platelet agglutination factor isolated from the venom of Taiwan habu (Trimeresurus mucrosquamatus)
Overview
Platelet glycoprotein Ib (GPIb)-binding proteins (GPIb-BPs) from snake, venoms are usually C-type lectins, which target specific sites of, GPIbalpha and elicit distinct effects on platelets. In the present paper, we report a tetrameric platelet-agglutinating factor (molecular mass 121.1, kDa), termed mucrocetin, purified from the venom of Taiwan habu, (Trimeresurus mucrosquamatus ). Mucrocetin is a GPIbalpha agonist with a, binding site distinct from that of flavocetin-A (a snake venom GPIbalpha, antagonist) on GPIbalpha, in spite of the high sequence identity (94.6%), between the two venom lectins. The crystal structure of mucrocetin was, solved and refined to 2.8 A (1 A=0.1 nm) resolution, which shows an, interesting crystal packing of six-layer cylinders of doughnut-shaped, molecules. The four alphabeta heterodimers are arranged in an unusual, square-shaped ring stabilized by four interdimer 'head-to-tail' disulphide, bridges. Detailed structural comparison between mucrocetin and, flavocetin-A suggests that their disparate platelet effects are probably, attributable to different charge distributions on the putative concave, binding surface. A unique positively charged patch on the binding surface, of mucrocetin, formed by Lys102, Lys108, Lys109 and Arg123 in the, alpha-subunit coupled with Lys22, Lys102, Lys116 and Arg117 in the, beta-subunit, appears to be the primary determinant of its, platelet-agglutinating activity. Conceivably, this interesting venom, factor may provide a useful tool to study platelet agglutination by, binding to the GPIb-IX-V complex.
About this Structure
1V4L is a Protein complex structure of sequences from Protobothrops mucrosquamatus. Full crystallographic information is available from OCA.
Reference
Crystal structure of a platelet-agglutinating factor isolated from the venom of Taiwan habu (Trimeresurus mucrosquamatus)., Huang KF, Ko TP, Hung CC, Chu J, Wang AH, Chiou SH, Biochem J. 2004 Mar 1;378(Pt 2):399-407. PMID:14613481
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