Fusion proteins for immune applications (FPIA)
are proteins constituted of binding domain(s) (usually from a receptor, membrane ligand, or cell-adhesion molecule) linked to immunoglobulin constant domains (Fc regions).
FPIA is an IMGT format-based classification for fusion Fc proteins used as an alternative to antibodies (antigen receptors). The Fc may be used for its effector proteins.
The term 'immunoadhesin' found in the literature to designate the first fusion proteins for immune applications is obsolete.