A Golgi retention signal in a membrane-spanning domain of coronavirus E1 protein

In an earlier study (26) , we found that deletion of the first and second membrane-spanning domains of El resulted in a mutant protein (Aml,2) which was efficiently transported to the plasma membrane. However, when the second and third membrane-spanning domains were deleted (Am2,3), the mutant protein was retained in the Golgi region of transfected cells. Both mutant proteins were inserted into and spanned the membrane properly. These results suggested that either the Golgi retention signal was in the first membrane spanning domain (ml), or that the deletion creating Oml,2 disrupted a retention signal elsewhere in the molecule . To distinguish between these two possibilities, we asked whether ml could retain a protein normally transported to the plasma membrane .