Characterization and molecular cloning of dabocetin, a potent antiplatelet C-type lectin-like protein from Daboia russellii siamensis venom

• Published in: Toxicon (Oxford) 2006, Vol.47 (1), p.104-112
• Main Authors: Zhong, Shu-Rong, Jin, Yang, Wu, Jian-Bo, Chen, Run-Qiang, Jia, Yong-Hong, Wang, Wan-Yu, Xiong, Yu-Liang, Zhang, Yun
• Format: Article
• Language: English
• Subjects: Adenosine Diphosphate - pharmacology; Amino Acid Sequence; Animals; Antibodies, Monoclonal - immunology; Antibodies, Monoclonal - metabolism; Base Sequence; cDNA sequence; Cloning, Molecular; Daboia russellii siamensis venom; DNA, Complementary - genetics; Electrophoresis, Polyacrylamide Gel; Flow Cytometry; Inhibitory Concentration 50; Lectins, C-Type - antagonists & inhibitors; Lectins, C-Type - genetics; Lectins, C-Type - isolation & purification; Molecular Sequence Data; Molecular Weight; Platelet Aggregation - drug effects; Platelet Aggregation Inhibitors - pharmacology; Platelet aggregation/agglutination; Platelet Glycoprotein GPIb-IX Complex - antagonists & inhibitors; Ristocetin - pharmacology; SV-CTLP; Viper Venoms - chemistry; Viper Venoms - genetics; Viper Venoms - pharmacology; Viperidae
• ISSN: 0041-0101; 1879-3150
• DOI: 10.1016/j.toxicon.2005.10.002

A novel C-type lectin-like protein, dabocetin, was purified from Daboia russellii siamensis venom. On SDS-polyacrylamide gel electrophoresis, it showed a single band with an apparent molecular weight of 28 kDa and two distinct bands with the apparent molecular weights of 15.0 kDa and 14.5 kDa under non-reducing and reducing conditions, respectively. cDNA clones containing the coding sequences for dabocetin α and β subunits were isolated and sequenced. The deduced protein sequences of both subunits were confirmed by N-terminal amino acid sequencing and trypsin-digested peptide mass fingerprinting. Dabocetin did not induce platelet aggregation in platelet-rich plasma. It also had little effect on the platelet aggregation induced by ADP, TMVA or stejnulxin. Whereas, dabocetin inhibited ristocetin-induced platelet agglutination in platelet-rich plasma in a dose-dependent manner with an IC 50 value of 0.35 μM. Flow cytometry analysis showed that dabocetin significantly inhibited mAb SZ2 binding to platelet membrane glycoprotein Ib alpha, indicating that platelet membrane glycoprotein Ib is involved in the inhibitory effect of dabocetin on ristocetin-induced platelet agglutination.