Ready-to-use ELISA kits are available for the detection of GP55, an alias of the protein, neuroplastin. The official gene symbol is NPTN. The protein, with a mass of 44.4 kDa and length of 398 residues, is reported to be membrane-associated. It may be known by other names, including: SDR1, SDFR1, GP55, stromal cell-derived receptor 1, stromal cell derived factor receptor 1, and SDR-1, and np65.