Complex formation between the spike protein and the membrane protein during mouse hepatitis virus assembly.

Using different approaches we have demonstrated the formation of a complex between the S protein and the M protein in the process of mouse hepatitis virus (MHV) assembly. Preservation of the M/S heterocomplexes was critically dependent on the solubilization conditions. Pulse-chase labeling of MHV-infected cells followed by a co-immunoprecipitation assay revealed that newly synthesized S and M engage in complex formation with different kinetics, the S protein reacting much slower. Sedimentation experiments showed the M/S heteromultimer complexes to be very large. A model for the role of the complex formation in MHV assembly is presented.