Lipid and Protein Composition of the Mammary Tumour Virus and the Milk Fat-Globule Membrane Isolated from the milk of infected Mice

Milk fat globule membranes and mammary tumour virus particles have been obtained from the milk of a swiss albino mice strain. Comparative biochemistry shows that these two structures differ significantly in the phospholipid, polypeptide and glycopeptide patterns and enzymatic activities. However, the lipid profile and the morphology of both structures suggest a filiation with the plasma membrane. Density fractions obtained from the crude virus preparation have been thoroughly investigated. The results sugget that most of these fractions represent degraded virus and/or atipycal virus assembly.