S1 region attaches the virion to the cell membrane by interacting with host ANPEP/aminopeptidase N, initiating the infection. Binding to the receptor probably induces conformational changes in the S glycoprotein unmasking the fusion peptide of S2 region and activating membranes fusion. S2 region belongs to the class I viral fusion protein. Under the current model, the protein has at least 3 conformational states: pre-fusion native state, pre-hairpin intermediate state, and post-fusion hairpin state. During viral and target cell membrane fusion, the coiled coil regions (heptad repeats) regions assume a trimer-of-hairpins structure, positioning the fusion peptide in close proximity to the C-terminal region of the ectodomain. The formation of this structure appears to drive apposition and subsequent fusion of viral and target cell membranes. Homotrimer. During virus morphogenesis, found in a complex with M and HE proteins. Interacts with host ANPEP. Accumulates in the endoplasmic reticulum-Golgi intermediate compartment, where it participates in virus particle assembly. The KxHxx motif seems to function as an ER retrieval signal. Bat coronavirus 512/2005 is highly similar to porcine epidemic diarrhea virus (PEDV). Belongs to the alphacoronaviruses spike protein family. In contrast to beta- and gammacoronaviruses, S glycoprotein is not cleaved into S1 and S2.