&ensp;</span>is <span  title="" class="an ">&ensp;</span>mediated <span  title="" class="an ">&ensp;</span>by <span  title="" class="an ">&ensp;</span>G <span  title="" class="an ">&ensp;</span>proteins <span  title="" class="an ">&ensp;</span>Under <span  title="" class="an ">&ensp;</span>current <span  title="" class="an ">&ensp;</span>clamp <span  title="" class="an ">&ensp;</span>both <span  title="" class="an ">&ensp;</span><span  title="CAP" class="an CAP">HT</span><span  title="" class="an ">&ensp;</