The rotavirus A membrane fusion protein complex including VP5 and 8, derived by proteolysis of VP4, as well as VP7, VP6 and VP2.  VP5, 8 and 7 may play primary roles while VP6 and 2 play secondary roles (Gilbert and Greenberg 1998; Golantsova et al. 2004; Settembre et al. 2011; Elaid et al. 2014).  These proteins from different viral strains may be very divergent in sequence.