Peptides containing a consensus Ras binding sequence from Raf-1 and theGTPase activating protein NF1 inhibit Ras function.
A key event in Ras-mediated signal transduction and transformation involves Ras interaction with its downstream effector targets. Although substantial evidence has established that the Raf-1 serine/threonine kinase is a critical effector of Ras function, there is increasing evidence that Ras function is mediated through interaction with multiple effectors to trigger Raf-independent signaling pathways. In addition to the two Ras GTPase activating proteins (GAPs; p120- and NF1-GAP), other candidate effectors include activators of the Ras-related Ral proteins (RalGDS and RGL) and phosphatidylinositol 3-kinase. Interaction between Ras and its effectors requires an intact Ras effector domain and involves preferential recognition of active Ras-GTP. Surprisingly, these functionally diverse effectors lack significant sequence homology and no consensus Ras binding sequence has been described. We have now identified a consensus Ras binding sequence shared among a subset of Ras effectors. We have also shown that peptides containing this sequence from Raf-1 (RKTFLKLA) and NF1-GAP (RRFFLDIA) block NF1-GAP stimulation of Ras GTPase activity and Ras-mediated activation of mitogen-activated protein kinases. In summary, the identification of a consensus Ras-GTP binding sequence establishes a structural basis for the ability of diverse effector proteins to interact with Ras-GTP. Furthermore, our demonstration that peptides that contain Ras-GTP binding sequences can block Ras function provides a step toward the development of anti-Ras agents.
Clark
G J
GJ
Department of Pharmacology, University of North Carolina, Chapel Hill, 27599, USA.
Drugan
J K
JK
Terrell
R S
RS
Bradham
C
C
Der
C J
CJ
Bell
R M
RM
Campbell
S
S
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D016384:Consensus Sequence; D004789:Enzyme Activation / Q000187:drug effects; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D025542:Neurofibromin 1; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology*; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry*; D011506:Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry*; D011518:Proto-Oncogene Proteins / Q000737:chemistry*; D019908:Proto-Oncogene Proteins c-raf; D016283:Proto-Oncogene Proteins p21(ras) / Q000037:antagonists & inhibitors*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000187:drug effects*
D025542:Neurofibromin 1; D010446:Peptide Fragments; D011506:Proteins; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D006160:Guanosine Triphosphate; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D020558:GTP Phosphohydrolases; D016283:Proto-Oncogene Proteins p21(ras)