Structural proteins and subunits of rubella virus

Polyacrylamide gel electrophoresis of purified rubella virus revealed two distinct structural proteins VP1 and VP3, which had molecular weights of 62,500 and 35,000, respectively. In addition, a broad variable peak, designated VP2, with a molecular weight of about 47,500, was seen. Sucrose gradient analysis of virus disrupted by neutral detergents separated a labile 150S ribonucleoprotein, containing 40S ribonucleic acid and VP3, from the envelope fraction containing VP1 and VP2. VP1 and particularly VP2 were labeled with glucosamine and are thus glycoproteins. Labeling the polypeptides with different amino acids indicated that VP3, the "core" protein, is relatively rich in arginine but not in lysine. The size of the two main polypeptides, VP1 and VP3, corresponds to those of group A arboviruses.