Fusion protein has two different meanings, one is the expression product of two genes recombined by DNA recombination technology. Another meaning is a group of proteins that mediate the fusion of two cell plasma membranes, such as one of the two glycoproteins contained in the outer leaflet of the Sendai virus lipid bilayer, which mediates the fusion of the virus envelope with the host cell plasma membrane. Another glycoprotein is hemagglutinin ceramidase.