1tn8
Protein Farnesyltransferase Complexed with a H-Ras Peptide Substrate and a FPP Analog at 2.25A Resolution
Structural highlights
FunctionFNTB_RAT Catalyzes the transfer of a farnesyl moiety from farnesyl pyrophosphate to a cysteine at the fourth position from the C-terminus of several proteins. The beta subunit is responsible for peptide-binding. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedPost-translational modifications are essential for the proper function of many proteins in the cell. The attachment of an isoprenoid lipid (a process termed prenylation) by protein farnesyltransferase (FTase) or geranylgeranyltransferase type I (GGTase-I) is essential for the function of many signal transduction proteins involved in growth, differentiation, and oncogenesis. FTase and GGTase-I (also called the CaaX prenyltransferases) recognize protein substrates with a C-terminal tetrapeptide recognition motif called the Ca1a2X box. These enzymes possess distinct but overlapping protein substrate specificity that is determined primarily by the sequence identity of the Ca1a2X motif. To determine how the identity of the Ca1a2X motif residues and sequence upstream of this motif affect substrate binding, we have solved crystal structures of FTase and GGTase-I complexed with a total of eight cognate and cross-reactive substrate peptides, including those derived from the C termini of the oncoproteins K-Ras4B, H-Ras and TC21. These structures suggest that all peptide substrates adopt a common binding mode in the FTase and GGTase-I active site. Unexpectedly, while the X residue of the Ca1a2X motif binds in the same location for all GGTase-I substrates, the X residue of FTase substrates can bind in one of two different sites. Together, these structures outline a series of rules that govern substrate peptide selectivity; these rules were utilized to classify known protein substrates of CaaX prenyltransferases and to generate a list of hypothetical substrates within the human genome. Crystallographic analysis of CaaX prenyltransferases complexed with substrates defines rules of protein substrate selectivity.,Reid TS, Terry KL, Casey PJ, Beese LS J Mol Biol. 2004 Oct 15;343(2):417-33. PMID:15451670[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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