The MET proto-oncogene encodes a transmembrane tyrosine kinase of 190 kDa (p190MET), which has recently been identified as the receptor for hepatocyte growth factor/scatter factor. p190MET is a heterodimer composed of two disulfide-linked chains of 50 kDa (p50α) and 145 kDa (p145β). We have produced four different monoclonal antibodies that are specific for the extracellular domain of the Met receptor. These antibodies immunoprecipitate with p190MET two additional Met proteins of 140 and 130 kDa. The first protein (p140MET) is membrane bound and is composed of an a chain (p50α) and an 85-kDa C-terminal truncated β chain (p85β). The second protein (p130MET) is released in the culture supernatant and consists of an α chain (p50α) and a 75-kDa C-terminal truncated β chain (p75β). Both truncated forms lack the tyrosine kinase domain. p140MET and p130MET are consistently detected in vivo, together with p190MET, in different cell lines or their culture supernatants. p140MET is preferentially localized at the cell surface, where it is present in roughly half the amount of p190MET. The two C-terminal truncated forms of the Met receptor are also found in stable transfectants expressing the full-length MET cDNA, thus showing that they originate from posttranslational proteolysis. This process is regulated by protein kinase C activation. Together, these data suggest that the production of the C-terminal truncated Met forms may have a physiological role in modulating the Met receptor function.
|Number of pages||9|
|Journal||Molecular and Cellular Biology|
|Publication status||Published - Dec 1991|
ASJC Scopus subject areas
- Cell Biology
- Molecular Biology