Analysis of membrane protein topography of Newcastle disease virus and cultured mammalian fibroblasts.

Diagonal electrophoresis, in conjunction with crosslinking by dimethyl-3,3'-dithiobispropionimidate (DTBP), has been used to probe membrane protein topography of Newcastle disease virus (NDV) and cultured mammalian fibroblasts (LM cells). Analysis of DTBP-treated NDV revealed crosslinking between a nucleocapsid protein, VP3, and an externally displayed glycoprotein, VP1, possessing hemagglutination and neuraminidase activities. Similar analysis of LM cells iodinated by the lactoperoxidase method indicated nearest-neighbor interactions of a noncovalent nature involving a major cell surface protein of 72,000 molecular weight. These studies illustrate the feasibility of this methodology for the study of membrane protein disposition in complex systems.