Structure-function studies of human cholesteryl ester transfer protein by linker insertion scanning mutagenesis.

摘要: Human plasma cholesteryl ester transfer protein (CETP) enhances and exchange of (CE) triglyceride (TG) between high-density lipoprotein other lipoproteins. To define regions responsible for the neutral lipid activities at molecular level, a total 27 linker insertion mutants 18 different sites along CETP molecule were prepared transiently expressed in mammalian cell line (COS). The inserted linkers small (usually 6 bp) did not interrupt translational reading frame cDNA. Although secretion each mutant was less than that wild-type CETP, majority had normal activity (transfer per nanogram media). However, insertional alterations three severely impaired CE activity: (1) region amino acids 48-53; (2) acid 165; (3) 373-379. could also be result globally incorrect folding these mutants, hydrophobicity analysis secondary structure predictions tended to exclude this possibility most which insertions resulted inactivation. 379 occurs immediately after triplet lysine residues, suggesting might involved an essential step mechanism TG transfer, such as binding phosphatidylcholine molecules surface. Effects on generally similar those activity, structural requirement both activities.