GPAA1(Glycosylphosphatidylinositol anchor attachment 1 protein) is also named as GAA1. It is the most conspicuously hydrophobic of the known subunits of GPIT, and it may play a key role in substrate recognition. It is predicted to be a multispanning membrane protein of 67 kDa with seven transmembrane (TM) domains, a large lumenal domain between the first two TM segments, and a cytoplasmically oriented N terminus bearing a potential ER retrieval signal in the form of a diarginine motif. It has 2 isoforms produced by alternative splicing and the full length protein has 2 glycosylation sites. This antibody is specific to GPAA1.