Chemical crosslinking of lipids and proteins within Mason-Pfizer monkey and squirrel monkey type D retroviruses

Nearest neighborhoods between lipids and proteins were investigated in Mason-Pfizer monkey virus (MPMV) and squirrel monkey retrovirus (SMRV) using the chemical crosslinking reagent dimethyl suberimidate (DMS). Analysis of DMS-induced lipid-protein complexes by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that in both viruses the major internal structural protein, p27 (MPMV) and p35 (SMRV), is linked to the lipid bilayer. Additionally, in SMRV a second protein (p20) was found to have a vicinal relationship to the lipid bilayer of the virus. Electron microscopic investigations of MPMV and SMRV particles indicated that, in accord with the crosslinking data, the core shell of these type D retroviruses is in close proximity to the viral membrane.