" class="an ">&ensp;</span>explain <span  title="" class="an ">&ensp;</span>a <span  title="" class="an ">&ensp;</span>fundamental <span  title="" class="an ">&ensp;</span>difference <span  title="" class="an ">&ensp;</span>between <span  title="" class="an ">&ensp;</span>native <span  title="" class="an ">&ensp;</span>and <span  title="" class="an ">&ensp;</span>recombinant <span  title="" class="an ">&ensp;</span>Kv <span  title="" class="an ">&ensp;</span>channels <span  title="" class="an ">&ensp;</span