MODULATION OF A MR 175,000 C-NEU RECEPTOR ISOFORM IN G8/DHFR CELLS BY SERUM STARVATION
- 25 June 1990
- journal article
- research article
- Vol. 265 (18) , 10746-10751
Abstract
The neu proto-oncogene product has been found to exist in two interconvertible forms in G8/DHFR mouse fibroblasts. The 185-kilodalton form (p185) present in growing cells is replaced by a 175-kilodalton form (p175) under conditions of serum starvation. This low molecular weight form accounts almost exclusively for the phosphotyrosine content of the receptor and is associated with increased tyrosine kinase activity. Addition of serum, platelet-derived growth factor or tumor promoter induces conversion of p175 to p185 within minutes, and this increase in molecular weight is associated with phosphorylation of serine and threonine; removal of serum growth factors is followed by replacement of p185 with p175 over several hours. Unlike G8/DHFR cells, the human breast cancer cell line SK-Br-3 expresses a high molecular weight neu/HER2 receptor with unchanged phosphotyrosine content in both serum-starved and serum-stimulated cultures. These findings indicate that activation of the neu proto-oncogene product in G8/DHFR cells may be regulated in part by protein kinase C-mediated receptor transmodulation rather than by ligand availability alone.This publication has 22 references indexed in Scilit:
- Molecular cloning of the neu gene: absence of gross structural alteration in oncogenic alleles.Proceedings of the National Academy of Sciences, 1986
- The neu oncogene: an erb-B-related gene encoding a 185,000-Mr tumour antigenNature, 1984
- Reduction of epidermal growth factor receptor affinity by heterologous ligands: Evidence for a mechanism involving the breakdown of phosphoinositides and the activation of protein kinase CBiochemical and Biophysical Research Communications, 1984
- Properties of a monoclonal antibody to epidermal growth factor receptor with implications for the mechanism of action of EGF.The EMBO Journal, 1984
- Human transforming growth factor-α: Precursor structure and expression in E. coliPublished by Elsevier ,1984
- Resolution of high and low affinity epidermal growth factor receptors. Inhibition of high affinity component by low temperature, cycloheximide, and phorbol esters.Journal of Biological Chemistry, 1982
- Modulation of Epidermal Growth Factor Receptors on 3T3 Cells by Platelet-Derived Growth FactorScience, 1980
- Electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets: procedure and some applications.Proceedings of the National Academy of Sciences, 1979
- Biologically active phorbol esters specifically alter affinity of epidermal growth factor membrane receptorsNature, 1979
- Direct visualization of binding, aggregation, and internalization of insulin and epidermal growth factor on living fibroblastic cellsProceedings of the National Academy of Sciences, 1978