title: Activation of the cellular proto-oncogene product p21Ras by addition of a myristylation signal.
abstract: The 21-kD proteins encoded by ras oncogenes (p21Ras) are modified covalently by a palmitate attached to a cysteine residue near the carboxyl terminus. Changing cysteine at position 186 to serine in oncogenic forms produces a nonpalmitylated protein that fails to associate with membranes and does not transform NIH 3T3 cells. Nonpalmitylated p21Ras derivatives were constructed that contained myristic acid at their amino termini to determine if a different form of lipid modification could restore either membrane association or transforming activity. An activated p21Ras, altered in this way, exhibited both efficient membrane association and full transforming activity. Surprisingly, myristylated forms of normal cellular Ras were also transforming. This demonstrates that Ras must bind to membranes in order to transmit a signal for transformation, but that either myristate or palmitate can perform this role. However, the normal function of cellular Ras is diverted to transformation by myristate and therefore must be regulated ordinarily by some unique property of palmitate that myristate does not mimic. Myristylation thus represents a novel mechanism by which Ras can become transforming.
authors.affiliation: La Jolla Cancer Research Foundation, CA 92037.
authors.forename: J E
authors.initials: JE
authors.lastname: Buss
authors.forename: P A
authors.initials: PA
authors.lastname: Solski
authors.forename: J P
authors.initials: JP
authors.lastname: Schaeffer
authors.forename: M J
authors.initials: MJ
authors.lastname: MacDonald
authors.forename: C J
authors.initials: CJ
authors.lastname: Der
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000502:physiology; D002471:Cell Transformation, Neoplastic / Q000503:physiopathology*; D015683:Gene Products, gag; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D019814:Myristic Acid; D009227:Myristic Acids / Q000502:physiology*; D011499:Protein Processing, Post-Translational; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D016283:Proto-Oncogene Proteins p21(ras); D012191:Retroviridae Proteins / Q000378:metabolism
chemical_list: D015683:Gene Products, gag; C000715470:MAS1 protein, human; D009227:Myristic Acids; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D012191:Retroviridae Proteins; D019814:Myristic Acid; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)