Structure-Function Relationships of The Gtp-Binding Domain of Elongation Factor Tu
Elongation factor Tu (EF-Tu) is a multifunctional enzyme, essential for protein synthesis in which it acts as the carrier of aa-tRNA to the ribosome-mRNA complex (Miller & Weissbach, 1977; Bosch et al., 1983; Parmeggiani & Swart, 1985). EF-Tu belongs to the class of guanine nucleotide-binding proteins which in recent years have been found to play a crucial role in controlling the transmission of information in fundamental processes of the eucaryotic and procaryotic cell, such as growth, hormone response, neurotransmission, membrane transport and protein synthesis (for refs: Masters et al., 1986; Dever et al., 1987; Gilman, 1987; Barbacid, 1987). In pathological processes guanine nucleotide binding proteins are involved in the oncogenic transformation of the human cell (Scolnick et al., 1979) and are encoded by the HIV retrovirus (Guy et al., 1987). In all of these proteins, the active form needed for the interaction with the various ligands, is the complex with GTP; their intrinsic GTPase activity cleaving the y-phosphate is therefore determinant for controlling their activity. The primary structure of this class of proteins shows a pronounced homology which in most cases affects the first 150–180 N-terminal amino acid residues. Functional, immunological and structural studies, and comparison with nucleotide binding proteins have led to the identification within these homologies of a consensus sequence involved in the binding of the substrate GTP/GDP (McCormick et al., 1985; Dever et al., 1987).
KeywordsGuanine Nucleotide Binding Protein Point Substitution Intrinsic GTPase Activity Molecular Weight Difference Protein Synthesis Initiation Factor
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