It was initially believed that the Sec61 channel is responsible for this retrograde transport, implying that transport through Sec61 is not always unidirectional but also can be bidirectional.
Críase inicialmente que o canal Sec61 era o responsable deste transporte retrógrado, o que implicaba que o transporte a través do Sec61 non era sempre unidireccional, senón que podía ser bidireccional.