Deletion mutagenesis pinpoints residues Phe463 to Leu475 as essential for both TP2 antibody binding and CETP's neutral-lipid-transfer activity (J Biol Chem 1992)

Original title: Identification of a sequence within the C-terminal 26 amino acids of cholesteryl ester transfer protein responsible for binding a neutralizing monoclonal antibody and necessary for neutral lipid transfer activity

J Biol Chem · 5 September 1992 · 9

Wang S, Deng L, Milne RW, Tall AR

Cholesteryl ester transfer protein (CETP; 476 amino acids) mediates neutral lipid and phospholipid transfer between plasma lipoproteins. The epitope of the neutralizing monoclonal antibody TP2 was previously shown to lie within CETP's C-terminal 26 amino acids. To probe this region's role in lipid transfer, the authors generated six deletion mutants between Arg451 and Leu475 and expressed them in mammalian cells. Only deletion mutants spanning Phe463 to Leu475 failed to bind TP2; these mutants were well secreted but showed markedly reduced cholesteryl ester transfer activity. One deletion mutant (delta470-475) showed similarly reduced cholesteryl ester and triglyceride transfer but normal or increased phospholipid transfer, with limited proteolysis indicating a folding pattern resembling wild type. Residues between Phe463 and Leu475 are thus necessary for TP2 binding, and deletions here selectively impair neutral lipid transfer.

Original abstract

The cholesteryl ester transfer protein (CETP; 476 amino acids) mediates the transfer of neutral lipids and phospholipids between plasma lipoproteins. Previous studies showed that the epitope of a neutralizing monoclonal antibody (TP2) was located within the C-terminal 26 amino acids (aa) of CETP. To determine possible involvement of this region in lipid transfer activities, we generated six deletion mutants between Arg-451 and Leu-475 by in vitro mutagenesis and expressed mutant proteins in mammalian cells. Only deletion mutants between aa Phe-463 and Leu-475 failed to bind TP2; these mutant proteins were well secreted by cells but showed markedly reduced cholesteryl ester transfer activity. One of the deletion mutants (delta 470-475) showed similar reductions in cholesteryl ester and triglyceride transfer activities but normal or increased phospholipid transfer activity. Limited proteolysis of this mutant protein indicated a similar overall folding pattern to the wild-type protein. Thus, aa between Phe-463 and Leu-475 are necessary for binding TP2. Deletions within this sequence selectively impair neutral lipid transfer activity, suggesting a direct involvement in neutral lipid transfer.

Summary written by cetpinhibition.org from the published abstract; figures as published. Page updated 19 August 2026. Methods.