ABSTRACT
The ability of polyoma virus to transform cells is dependent on expression of a protein known as middle - T antigen. The combination of molecular cloning techniques and protein purification have revealed the presence of a multiplicity of enzymes that hydrolyze polyphosphoinositides. Translocation from the cytosolic compartment to the membrane as a result of the covalent modification of phospholipase-C, guanosine triphosphate-binding proteins, or other enzymes and proteins of regulatory significance could also underly the ‘priming’ response seen with some growth factors. The studies described above have emphasized the important role of tyrosine kinases in the regulation of signaling pathways involving inositol lipids. The studies described above have emphasized the important role of tyrosine kinases in the regulation of signaling pathways involving inositol lipids.
