Fig. 1

Alignment and surface potential analysis of crucial amino acids in AXL proteins. (A) Comparative analysis of the residues of AXLs at the interface binding to the spike of SARS-CoV-2 from human (GenBank accession no. NP_068713.2), rhesus (GenBank accession no. XP_028695606.1), hamster (GenBank accession no. XP_035292416.1), mouse (GenBank accession no. XP_006540052.1), ferret (GenBank accession no. XP_004776133. 1), mink (GenBank accession no. XP_044113292.1), and chickens (GenBank accession no. NP_989958. 2). ALX residues at position 61, 68, 113, 115, and 116 are marked in blue triangles. (B) Surface diagram of interface zone of AXLs. The structural superposition of the AXL region 29–127 from human (yellow, PDB code 4yfg), rhesus (violet), hamster (purple), mouse (gray), ferret (cyan), mink (red), and chickens (green). The AXL structures of chickens, rhesus, hamster, mouse, ferret, and mink were constructed using the homology models of human AXL (PDB code 4yfg) as the templates by SWISS-MODEL (https://swissmodel.expasy.org/). The five key differential residues of AXL interacting with spike protein of SARS-CoV-2 are represented by yellow sticks in the structural superposition, the black dash line circled key residues in the potential surface diagram. The electrostatic potential color range is -/+5