concentrations of herg1a crna injected alone faint bands corresponding to the immature and mature herg1a proteins were detected the co injection of herg1a and sig1r crna resulted in a clear increase in the two herg1a proteins fig7 a top in the western blot experiments carried out with the herg1b mrna only the immature band of 80 kda could be clearly detected which is in agreement with the previous results demonstrating that the herg1b trafficking efficiency is down modulated in the absence of herg1a subunits 17 once again the co injection of herg1b with the sig1r crna caused a clear increase in the intensity of the 80 kda band fig7 a bottom on the other hand the expression of sig1r did not increase the herg protein level when high concentrations of sig1r crna 15 ng oocyte were injected not represented these results showed that the expression of sig1r stimulates the herg current via an increase in the amount of herg channel thus these experiments conclude that sig1r stabilizes the channels at the plasma membrane the existence of a direct interaction between herg and sig1r was explored in xenopus oocytes via the injection of crna of herg1a or of herg1a cmyc sig1r it should be noted that it has been demonstrated that sig1r tagged with cmyc in the nh 2 terminal portion is functionally expressed in hek293 cells 9 and increases the herg current in xenopus oocytes in the same way as native sig1r crna does not represented the sig1r receptors were immunoprecipitated using an antibody directed against the cmyc tag and the result of the immunoprecipitation was resolved on an sds page gel the western blot was visualized using the anti pan herg antibody and the anti sig1r antibody as shown in fig7 b in the oocytes co injected.