Anti-GP55 antibodies are protein reagents that detect specific antigens. The GP55 antigen is another term for the human protein neuroplastin, encoded by the NPTN gene. The protein is a suspected homophilic and heterophilic cell adhesion molecule involved in long term potentiation at hippocampal excitatory synapses through activation of p38MAPK. Canonically, it has an amino acid length of 398 residues and a mass of 44.4 kilodaltons. Its subcellular localization is in the cell membrane and it is widely expressed in many tissue types. Other alias names for GP55 include GP65 and SDFR1.