SIGNALING PROTEIN, GTPASES, H-RAS, NOONAN SYNDROME, ACETYLATION, CELL MEMBRANE, DISEASE MUTATION, GOLGI APPARATUS, GTP-BINDING, LIPOPROTEIN, MEMBRANE, METHYLATION, NUCLEOTIDE-BINDING, PALMITATE, PRENYLATION, PROTO-ONCOGENE, S-NITROSYLATION 3I3S CRYSTAL STRUCTURE OF H-RAS WITH THR50 REPLACED BY ISOLEUCINE