Antigen Receptors IgM and IgD (IMAGE) BIOSS - Centre for Biological Signalling Studies Caption Researchers previously assumed that receptors such as the antigen receptors of class Immunoglobulin M and Immunoglobulin D are freely diffusing and equally distributed molecules on the membrane (image above). However, the new study shows that these antigen receptors are organized in different membrane compartments, also called 'protein islands', with diameters of 150-200 nanometers (image below). This finding is another indication that, at nanoscale distance, the proteins on cellular membranes are highly organized. Credit Research Group Reth/BIOSS Usage Restrictions The image may only be used with the appropriate caption and credit. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.