In order to further explore the possible contribution of N TAIL regions other than the a-MoRE to XD binding, we have looked at the regions of homology conserved amongst members of the Morbillivirus genus (Diallo et al. 1994) . These regions of homology are herein referred to as Box1, Box2, and Box3 and span N residues 401-420, 489-506, and 517-525, respectively (see Fig. 3A ), with the a-MoRE being located within Box2. We have then designed three deletion constructs bearing different combinations of these homology boxes (Fig. 3A) .