Showing papers by "Luigi Naldini published in 1985"
01 Jan 1985
TL;DR: Putative substrates of tyrosine kinases have been identified by means of conventional techniques such as bidimensional separation of total cellular proteins followed by phosphoaminoacid analysis, but these techniques seem to have intrinsic limitations - as shown by the failure to identify well known substrates - such as the transforming proteins themselves, which are known to be heavily tyosine-phosphorylated.
Abstract: The transformation process induced by several retroviruses, including Rous sarcoma virus (RSV), Feline sarcoma virus (FeSV), Fujinami avian sarcoma virus (FSV) and Abelson murine leukemia virus (AMuLV), is triggered and maintained by the action of v-onc genes which all code for transforming proteins with associated tyrosine kinase activity (for review see 1). Since protein phosphorylation seems to be invariably associated with molecular mechanism(s) involved in growth control and in the neoplastic transformation triggered by these retroviruses, the identification of cellular proteins phosphorylated at tyrosine residues is an issue of major importance. Putative substrates of tyrosine kinases have been identified by means of conventional techniques such as bidimensional separation of total cellular proteins followed by phosphoaminoacid analysis. However, these techniques seem to have intrinsic limitations - as shown also by the failure to identify well known substrates - such as the transforming proteins themselves, which are known to be heavily tyrosine-phosphorylated. The difficulties are generated by the fact that phosphotyrosine represents less than 2% of phosphoaminoacids also in transformed cells (being less than 0.2% in normal cells); in addition it has been shown that, only a minor fraction, i.e. less than 10%, of each substrate molecules of v-onc coded kinases, is phosphorylated at tyrosine even in fully transformed cells.