Skip to main content
. Author manuscript; available in PMC: 2021 Jun 1.
Published in final edited form as: Nat Protoc. 2020 Oct 26;15(12):3777–3787. doi: 10.1038/s41596-020-00403-2

Figure 1. Schematics of COVID-19 GEMM designs, category 1: Knocking-in expression cassettes or point mutation changes into the endogenous mouse Ace2 locus.

Figure 1.

(A) KO:KI design; human ACE2 cDNA (GEMMs #1, #3 and #5) or human ACE2 cDNA fused to P2A-EGFP GEMMs #2, #4 and #6) will be inserted in place of mouse Ace2 by deleting about 48kb of genomic sequence between the start and stop codons of mAce2. (B) Key amino acids KI design (GEMMs #7 to #9); only the key amino acids that differ between mouse and human and are responsible for binding to the spike protein, will be replaced by knocking-in an ssODN donor containing the humanized codons. The locations of amino acids N31K, S82M and H353K are shown. (C) KO:KI designs to co-express hACE2 and hTMPRSS2 (GEMMs #10 to #15). P2A: a self-cleavable viral peptide used for expressing two fusion proteins. IRES: Internal Ribosomal Entry Site.