| HERG(Human ether-a-go-go-related gene)potassium process exception access door control can form a variety of diseases,such as arrhythmia,long QT syndrome,many traditional Chinese medicine compound is by influencing the hERG potassium channel gating process to exert its antiarrhythmic effect,such as tree fruit base,puerarin,rhy,berberine,lotus nut alkali plant extracts,such as by inhibiting hERG potassium current,prolong multipole treating ventricular acceleration and ventricular fibrillation.Therefore,it is very important to understand the mechanism of the gating process of hERG potassium channel.It has been reported that mutation of Y403 to alanine will affect the gating process of the channel,but its mechanism is not clear.In this paper,the mechanism of regulating hERG potassium channel gating at Y403 was studied by constructing ion channel mutants and patch clamp technique.First,The results show that the Y403A mutation can accelerate the activation process and the deactivation process of the channel.The S631A channel does not affect the activation process of the channel,and the C-type deactivation of the channel is eliminated.This part repeats the previous experiments and is consistent with the previous experimental results,and ensures the consistency and credibility of the experiment.In addition,from the experimental results,it is assumed that there is N-type inactivation in the hERG potassium channel,and the Y403 site will affect the process.The effect of Y403A and S631A with the elimination of C-type deactivator is investigated.The results show that Y403AS631A double-mutation channel slows down the activation process of the channel,but the de-activation process of the channel is accelerated.It is reported that the N-terminal 138-373 amino acid chain can interact with the S620T mutant inside the channel mouth to slow the de-activation process of the channel,and the S631A is the same as the S620T function(both can eliminate the C-type inactivation)and the position is close(both at the inner side of the channel mouth),It is assumed that S631A will also interact with the N-terminal 138-373 amino acid chain to slow the deactivation of the channel.On the basis of Y403AS631A double mutation channel,138-378 amino acid chain,2-354 amino acid chain and 2-135 amino acid chain of N-terminal were removed respectively.The results showed that the removal of 138-373 amino acid chain would accelerate the activation process of channel and slow down the deactivation process of channel.As a control,138-373 amino acid chain of N-terminal was also removed from wild type and s631a.The results also showed that the removal of 138-373 amino acid chain of N-terminal would accelerate the activation process of channel Activation slows down the deactivation of the channel.The removal of 2-354 amino acid chain and 2-135 amino acid chain will accelerate the process of channel deactivation.According to the experimental results,it is suggested that there may be n-type inactivation in the potassium channel of ERG,and the N-terminal 138-373 amino acid chain may affect this process.The mechanism of n-type inactivation is the ball-chain mechanism,in which some amino acids(about 20)at the alpha subunit n-terminal of the channel bind to the inside of the channel channel region and cause channel inactivation.In order to further explore the existence of n-type inactivation,it is assumed that the site of 138-373 long chain action may be located in the S6 region,and it is also speculated that Y403 may interact with the structural domain of S6 to activate the action.Some mutation studies were carried out in the S6 domain,and the actual results showed that after mutating glutamine at 664 position to alanine on the basis of Y403AS631A,the activation process of the channel was accelerated and the deactivation process of the double mutation channel of Y403AS631A was slowed down,indicating that Y403 could interact with Q664 to affect the gating process of the channel.According to the experiment,it is speculated that there is n-type inactivation in hERG potassium ion channel.Q664 may affect the n-type inactivation of hERG potassium ion channel just as removing the 138-373 amino acid chain at the n-terminal,and they may affect the gating process of the channel with the same mechanism.138-373 long chain amino acid is "ball",and the position of 664 May be the receptor of 138-373 long chain structure.The interaction between the two plays a role of a chain,making 138-373 long chain structure block the ion channel hole and inactivate the ion channel.However,Y403 may affect the n-type inactivation by acting on the 664 position of the S6 domain. |
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