Severe acute respiratory syndrome Coronavirus (SARS-CoV), middle eastern respiratory syndrome Coronavirus (MERS-CoV), and the recently identified novel Coronavirus (SARS-CoV-2) belong to the Coronaviridae family, genus Betacoronavirus, that has been related to important epidemiological outbreaks. SARS-CoV emerged in 2003 as a significant threat to human health. SARS-CoV has four structural proteins, known as the S (spike), E (envelope), M (membrane), and N (nucleocapsid) proteins. The spike protein, responsible for allowing the virus to attach to and fuse with the membrane of a host cell and is a large type I transmembrane protein containing two subunits, S1 and S2. S1 mainly contains a receptor binding domain (RBD), which is responsible for recognizing the cell surface receptor. S2 contains basic elements needed for the membrane fusion. The S protein plays key parts in the induction of neutralizing-antibody and T-cell responses, as well as protective immunity. It attaches the virion to the cell membrane by interacting with host receptor, initiating the infection. A metallopeptidase, angiotensin-converting enzyme 2 (ACE-2), has been identified as a functional receptor for SARS-CoV through interaction with a receptor binding domain (RBD) located at the C-terminal of S1 subunit. Recombinant protein corresponding to aa306-515 from SARS-CoV Spike RBD, fused to His-Tag at C-terminal, expressed in HEK293 cells. Molecular Weight: ~24.8kD Biological Activity: Measured by its binding ability in a functional ELISA with Human ACE-2 Amino Acid Sequence: RVVPSG DVVRFPNITN LCPFGEVFNA TKFPSVYAWE RKKISNCVAD YSVLYNSTFF STFKCYGVSA TKLNDLCFSN VYADSFVVKG DDVRQIAPGQ TGVIADYNYK LPDDFMGCVL AWNTRNIDAT STGNYNYKYR YLRHGKLRPF ERDISNVPFS PDGKPCTPPA LNCYWPLNDY GFYTTTGIGY QPYRVVVLSF ELLNAPATVC GPKL Storage and Stability: May be stored at 4C for short-term only. Aliquot to avoid repeated freezing and thawing. Store at -20C. Aliquots are stable for 6 months after receipt at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.