A. Kazlauskas, C. Ellis, T. Pawson, J.A. Cooper, "Binding of GAP to activated PDGF receptors," Science, 247:1578-81, 1990.
Andrius Kazlauskas (National Jewish Center for Immunology and Respiratory Medicine, Denver): "The GTPase activator protein of ras (GAP) is one of a number of recently discovered proteins that appear to maintain nucleotide binding proteins such as ras in an inactive state, that is, coupled with GDP instead of GTP. Since regulation of GAP activity could affect cellular levels of activated ras, and platelet-derived growth factor (PDGF)-induced mitogenesis appears to require increased concentration of activated ras, we examined changes in GAP following PDGF stimulation. We found that GAP becomes tightly associated with the PDGF receptor (PR) in PDGF-stimulated cells, but not in unstimulated cells. Since binding of GAP to the activated PR correlates with increased levels of activated ras, it is possible that PR-bound GAP is less able to maintain ras in its ...
