Amino acid alignment of the N-terminal CEACAM1 IgV domain.

(A) Alignment of the N-domain of CEACAM1 with other members of the CEA family. Interface 1 and 2: # symbols indicate the position of mutated amino acids in CEACAM1 that affect YTH71.3.2 Mab or Opa protein binding, respectively. Peptide sequences that regulate the expression of CD11/CD18 and L-selectin levels on neutrophils are both underlined in pink and the residues are shown in green or pink. Interface 3 and 4: # symbols indicate the position of mutated amino acids in CEA or CEACAM8, respectively, that affect Opa protein binding in reference 52. The amino acid sequence that is critical for mouse CEACAM1 binding to murine corona viruses is indicated in brown and underlined. Amino acids in CEACAM1 conserved in other family members are indicated in bold type (100% identity); gaps are denoted by dashes (–). Strand indicates secondary structure elements and β strand positions are underlined and marked under the sequence and lettered A to G. (B) Alignment of the N-domain of CEACAM1 with human (H) and rat (R) CD2 and human CD58. Interface 5: Red # symbols represent the position of mutants that abrogate CEACAM1 homophilic interactions. Blue # symbols represent the position of mutants that abrogate anti-CEACAM Mab binding. For the CEACAM1 [H] sequence, residues in red are those mutated in this manuscript. Interface 6 and 7: # symbols indicate known amino acid residues at the interface in human CD2 and CD58, respectively. These are based on x-ray crystallographic coordinates for human and rat CD2 and human CD58.25-27 Mutated human CEACAM1 residues are indicated by arrows, with each amino acid being substituted with alanine (A) either as a single, double, or triple mutant or with arginine (R) for D82 or aspartic acid (D) for R64 as indicated in Figures 3, 6, and 7 and Table 1.