FIG 3.

Primary amino acid sequence and characteristic structural features of the Dasy-Env1.1 and Dasy-Env1.4 retroviral envelope proteins. The SU and TM subunits are delineated, and the furin cleavage site (consensus, R-X-R/K-R) between the two subunits together with the CWLC and CX6CC domains involved in the SU-TM interaction are indicated. The hydrophobic signal peptide, the fusion peptide, the transmembrane domain, and the putative immunosuppressive domain (ISD) are also indicated. The canonical SDGGGX2DX2R motif involved in syncytin-1/hASCT2 interactions is shaded in gray. Of note, this motif is degenerate in Dasy-Env1.4, consistent with the lack of fusogenicity of this gene (see Results).