Analysis of the role of the extracellular domain of the v-erbB oncogene in cellular transformation.

The role of the extracellular domain of the v-erbB oncogene in the transformation of chicken fibroblasts and erythroblasts has been examined. A virus was isolated in which the complete extracellular domain and the transmembrane domain of the v-erbB were replaced with sequences from the gag and env genes. The resulting virus, GEE35, was capable of transforming both fibroblasts and erythroblasts as efficiently as wild-type v-erbB. Biochemical and immunochemical analysis of the v-erbB protein encoded by GEE35 revealed two proteins of apparent molecular weights of approximately 130,000 daltons. One of these proteins was an N-linked glycosylated membrane protein, whereas the other was cytoplasmic. The possible roles of either of these two proteins in transformation is discussed.