We downloaded complement-related sequences from the UniProt database to determine which viral proteins contain the C1q domain. Then, using native MEME tools, compare these sequences to viral proteins to identify conserved domains. Due to the more number of motifs, we combined the motif search results by protein and domain. The C1q domain motifs of the SARS-COV-2 virus proteins are listed in Table . As demonstrated in Table , structural proteins (S, E, M, and N) and non-structural proteins (ORF3a, ORF6, ORF7a, ORF7b, ORF8, ORF10, nsp2, nsp4, 3c-like) contain C1q domain motifs. nsp2, nsp4, and 3c-like all have concise C1q motifs. Among the four S C1q A-D motifs, the relatively conservative C-terminal regions of S C1q C and D are required for membrane fusion. S C1q C is located in the EF-hand region and has a spherical area, activating S2 and initiating membrane fusion. S C1q A and B are located at the N terminal. S C1q A is in the S1 protein's globular head region. S C1q is homologous to the TryThrA_C domain of the Plasmodium falciparum antigen. As the trimeric structure of the S protein, its C1q domains were able to bind complement receptor 1 in the red blood cell membrane.