New Technique Developed to Identify Clusters of Proteins on the Plasma Membrane of Immune Cells

New Technique Developed to Identify Clusters of Proteins on the Plasma Membrane of Immune Cells

【期刊名称】中国科学院院刊（英文版）【年(卷),期】2014(028)004【总页数】2

When our bodies are under attack from foreign organisms, such as bacteria and viruses, our immune system orchestrates a complex fight-back involving many separate parts. One important component of this response is a type of cell called the B-lymphocyte - it is this cell that is at the forefront of our defence as it identi fi es and attempts to neutralise invaders.

The B-lymphocyte produces a protein called the B-cell receptor on its surface. The receptor recognises and attaches itself to molecules from the invading organisms, known as antigens. This triggers the B-lymphocyte to divide and to release specialised proteins called antibodies which neutralise the antigens.

There are many aspects of this process that are still not well understood. One reason is because the B-cell receptor does not exist in isolation on the B-lymphocyte surface. Rather, it forms localised clusters together with a number of ‘molecular neighbours’. It is these local interactions that control how the lymphocytes divide and replicate and determine the strength of the antibody response. A better understanding of these interactions could ultimately lead to better control of the immune response - for example in vaccine

development. However, the molecular contacts within the clusters are relatively weak, and so they are technically dif fi cult to identify.

Now, in an international collaboration, scientists atthe CAS Institute of Biophysics (IBP), the University of Cambridge’s Department of Biochemistry and the Cambridge Centre for Proteomics have developed a technique that allows some of these molecules to be detected. It is published in the 23rdMay edition of theJournal of Biological Chemistry. The method enables proteins in the immediate vicinity of the B-cell receptor to be chemically tagged in such a way that they can be more easily isolated. The tagged molecules can then be identi fi ed using a method called mass spectrometry.

For this initial “proof of principle” experiment, the researchers looked at the B-cell receptor on the surface of a chicken B-lymphocyte and identi fi ed molecules that were