Studies On The Synthesis Of CD36 Transmembrane Peptides And Mechanism Of Transmembrane Domain Interactions

As a transmembrane glycoprotein, CD36 is multi-functional cell membrane receptor. As the fat taste receptor, the study of obesity and diseases related to excessive fat intake has an important significance. In addition, as oxidized low density lipoprotein (Ox-LDL) in the high affinity receptor, it can recognise and endocytose by Ox-LDL and lead to foam cell formation and the occurrence of atherosclerosis. Therefore, it can be provide ideas for the further design of new drugs in the study of the mechanism in structure and function of CD36.In this thesis, compared the CD36 protein in various species through the NCBI protein database, we can obtain CD36 N-terminal and C-terminal that exist highly conserved transmembrane domain respectively. Due to the interaction of CD36 transmembrane domain has important significance for transmembrane signal transduction, at first we used solid phase chemical synthesis (SPPS) to get CD36 transmembrane peptides in this paper, circular dichroism showed peptide as a typical a-helical characteristic. Then we used by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and fluorescence resonance energy transfer (FRET) method to study the interaction of CD36 transmembrane domain. SDS-PAGE showed N-terminal TM domain peptide of protein CD36 existence dimerization, corresponding to C-terminal TM domain peptide runs as a monomer. We have also used FRET to measure dimerization of CD36 N-terminal TM domain peptide in SDS micelles by labled Pyrene and Coumarin as a donor-acceptor pair, they can be formed dimerization assembly.Since these findings were obtained in the simulation environment of cell membrane, and then we have used the TOXCAT assay system for the study of transmembrane helix-helix oligomerization in the inner membrane of E.coli, to study TM association in a natural membrane environment, also indicate that internal environment of E.coli only the existence of N-terminal TM domain structure of the dimerization. Mutating either one of Gly residues (G16 or G20) to Ile or Ala disrupted CD36 TM dimerization indicated that GXXXG motif were critical for CD36 TM homo-oligomeric interaction in membranes. Through the above studies provide a better understanding of identified transmembrane protein CD36 receptor and its corresponding role in the interaction between methods and principles, which determine the transmembrane domain of transmembrane signal transduction in the immune system played a key role in further immune from the molecular level. It can explain the mechanism of signal transduction for the transmembrane domain peptides and provide a theoretical basis for new drugs.