To reveal the mechanism of MHC-I peptide assembly complex screening protein fragment from structure

Today, social media helps us keep up with the times Because we can't process a lot of information at the same time, neural network only extracts the information we need to know Our cells work in a similar way: in the process of resistance to parasites, viruses and even cancer, a molecular machine called MHC-I peptide loading complex selects protein fragments that are important to the immune system In a new study, researchers from the Max Planck Institute of Biophysics in Germany, Frankfurt University and Martin Luther University have elucidated the structure and working mode of the protein complex Relevant research results were published online in the nature Journal on November 6, 2017, with the title of "structure of the human MHC-I ptide loading complex" In cells, state updates in the form of small protein fragments (peptides) carry information from the inside of the cell These peptides are presented to the cell surface by the MHC-I protein so that they can be detected by the immune system MHC-I molecules rapidly transmit information about cancer cells or virus infected cells to the immune system This allows the immune system to recognize degraded or infected cells and destroy them However, transmitting the wrong information can lead to autoimmune diseases or chronic inflammation "To study the structure of this extremely fragile MHC-I peptide assembly complex, we first developed a molecular bait," explains Simon trowitzsch of the center for biology at Frankfurt University With this tool, we can separate this complex from the endoplasmic reticulum " Arne m ö ller of the Max Planck Institute of Biophysics added, "thanks to the breakthrough in the field of cryomicroscopy, we can directly observe the MHC-I peptide assembly complex and clarify its structure." In order for cells to provide information to the immune system, membrane transporters, folding enzymes and MHC-I molecules must work together precisely in a complex The results of this study show how the MHC-I peptide assembly complex filters out only those protein fragments recognized by immune cells "These findings are very important because viruses and cancer cells interfere with information transmission and can be smarter than the immune system," said Robert tamp é of the Institute of Biochemistry at the University of Frankfurt We now have a better understanding of how cells choose to fight the cancer or infection they originally tested for This may help improve immunotherapy "