Fcab

{{short description|Antibodies fragments}}

{{about|the antibodies|the South American railway known as FCAB|Ferrocarril de Antofagasta a Bolivia}}

Fcabs are antibodies fragments engineered from the constant region of an antibody (Fc).{{cite journal |vauthors=Wozniak-Knopp G, Bartl S, Bauer A, Mostageer M, Woisetschläger M, Antes B, Ettl K, Kainer M, Weberhofer G, Wiederkum S, Himmler G, Mudde GC, Rüker F | title=Introducing antigen-binding sites in structural loops of immunoglobulin constant domains: Fc fragments with engineered HER2/neu-binding sites and antibody properties. | journal=Protein Eng Des | year=2010 | volume=23 | issue=4 | pages=289–297 | pmid=20150180 | doi=10.1093/protein/gzq005| doi-access=free }} In naturally occurring antibodies (such as IgGs), the antigen-binding sites are located at the variable regions (Fab).