Purity > 85% as determined by SDS-PAGE. MW: 21.4kDa. Full Length: 1-46aa. N-terminal 6xHis-sumostar-tagged. Homo sapiens (Human). Moderately selective excitatory receptor for orexin-A and, with a lower affinity, for orexin-B neuropeptide. Triggers an increase in cytoplasmic Ca2+ levels in response to orexin-A binding