ABSTRACT
Objective To construct a CaME141G fusion protein-expressing plasmid,and to express,purify,and identify the activity of the recombinant protein. Methods The 141st site of the wild type CaM,E (GAG),was mutated to G (GGG),using site-specific mutagenesis technology. Escherichia coli BL-21 was transformed with the mutant plasmid. The GST-CaME141G fusion protein was mass-cultured and induced for expression. Subsequently,the GST-CaME141G fusion protein was purified using GS-4B beads. PreScission protease was applied to remove the GST,the Bradford method used to determine the concentration of purified protein,and SDS-PAGE used to detect its relative molecular weight and purity. The GST pull-down assay was used to study the protein's biological activity. Results The CaME141G protein was successfully purified at a high concentration and purity. The protein could interact with PreIQ protein fragments from the myocardial CaV1. 2 calcium channel C terminal,in a CaME141G concentration-dependent manner. Therefore,CaME141G has the ability to bind with the CaV1. 2 calcium channel. Conclusion This study successfully constructed a CaME141G fusion protein-expressing plasmid and purified the CaME141G protein. This lays a foundation for regulating the function of CaM mutations in the myocardial CaV1. 2 calcium channel,and for the study of its relationship with diseases of the cardiovascular system.
ABSTRACT
Aim To construct 3 D structure model of cardiac Cav1.2 channel and check its accuracy and re-liability.Methods Homology model of Cav1.2 chan-nel α1 subunit was constructed using SWISS-MODEL server.The model was submitted to an online testing server built by University of California and scored by it.The binding of Cav1.2 channel with blocker or drug was simulated by MOE software molecular docking pro-gram to check the model′s accuracy and reliability.Re-sults Both the target sequence Cav1.2 α1 C and the template sequence Cav1.1 α1 S searched by SWISS-MODEL server belonged to L-type Ca2+channel.Since the homology was 7 1.5% revealed by sequence align-ment,homology modeling was performed using automa-ted mode.L-type Ca2+ channel blockers Verapamil, Nifedipine and Diltiazem could bind to the 3 D structure model of Cav1.2 channel,while sodium channel bloc-ker TTX could not.Furthermore,active ingredient of traditional Chinese drug Praeruptorin A and Berberine could also bind to the 3D structure model of Cav1.2 channel.Conclusion The 3 D structure model of Cav1.2 channel was constructed successfully,which provides reliable materials for further studies and estab-lishes the foundation for the application of homology modeling in the study of 3 D structure prediction of ion channels.
ABSTRACT
Objective To investigate a method for the purification of the N?terminal peptide fragment(NT)of the myocardial calcium channel Cav1.2,and characterize its interaction with calmodulin(CaM). Methods EscherichiacoliBL?21 cells were transformed with plasmid pGEX?6p?3/NT harboring the NT?GST fusion gene. The cells harboring pGEX?6p?3/NT were cultured and protein expression was induced with isopropyl?β?D?thiogalactoside(IPTG). Then,the GST?NT fusion protein was purified by using glutathione Sepharose 4B(GS?4B)beads. GST was cleaved off with the PreScission protease,and SDS?PAGE was performed to detect the purity and relative molecular weight of the purified peptide. Further, GST pull?down assay was performed to characterize the interaction of the NT peptide with CaM. Results SDS?PAGE analysis showed that the NT peptide was successfully purified,with high purity. Results of the GST pull?down assay showed that the NT peptide could interact with CaM. Conclusion This study establishes a method for the purification of the NT peptide and lays the foundation for further research on the interaction partners and biological functions of NT.