Role of the GTNGTKR motif in the N-terminal receptor-binding domain of the SARS-CoV-2 spike protein

•SARS-CoV-2 S1-NTD presents different receptor binding motifs compared to the SARS-CoV.•Functional motifs similar to the S1-NTD GTNGTKR loop were identified in other proteins.•The GTNGTKR loop is very likely to allow the SARS-CoV-2 to bind other receptors.•The GTNGTKR motif is very likely an evolutionary acquisition under functional constraints.