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. 2021 Feb 27;41:100853. doi: 10.1016/j.nmni.2021.100853

Fig. 1.

Fig. 1

Schematic overview of genome, genes and proteins of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). (A) SARS-CoV-2 genome comprises positive-sense, single-stranded RNA (ssRNA) genome 27 to 32 kb in size. The 5′ terminus (translated from first ORF1a and ORF1b) encodes two large polyproteins, pp1a and pp1ab, which are proteolytically cleaved into 16 nonstructural proteins (NSPs), including papain-like protease (PLpro), 3C-like protease (3CLpro) and RNA-dependent RNA polymerase (RdRp). An additional 9 to 12 open reading frames (ORFs) are encoded through transcription of nested set of subgenomic RNAs. The 3′ terminus encodes structural proteins, including envelope glycoproteins spike (S), envelope (E), membrane (M) and nucleocapsid (N). (B) Percentage distribution of transcription factor (TF) binding sites in different genomic regions of SARS-CoV-2, as follows: ORF1ab, open reading frame 1ab; S, protein S; ORF3a, open reading frame 3a; E, protein E; M, protein M; ORF6, open reading frame 6; ORF7a, open reading frame 7a; ORF7b, open reading frame 7b; ORF8, open reading frame 8; N, protein N; ORF10, open reading frame 10.