A vertebrate’s first line of defense against pathogens are antibodies. An antibody receptor, pIgR (polymeric immunoglobulin receptor) is conserved across vertebrates from fish to humans, and a piece of the receptor comes off and becomes part of the antibody package to help stabilize the antibody. However, researchers have noted that sometimes the secreted pIgR piece, without an antibody, is released, and surprisingly can bind to bacteria by themselves. But the structure of that piece, and how it interacts with bacteria and antibodies was unknown. Now Beth Stadtmueller and colleagues in the lab of ASCB member Pamela Bjorkman at the California Institute of Technology solved the structure of the secretory pIgR and show that it uses multiple confirmations to protect against pathogens and other external agents. Published in eLife.
