Table 1. Nucleotide and amino acid sequence similarities of PD-1 among vertebrate species.
| Species (GenBank accession number) | Dog | Cat | Cattle | Pig | Human | Rhesus monkey | Mouse | Rat |
| Dog | - | 83.4 | 78.1 | 78.5 | 76.4 | 77.3 | 69.2 | 69.0 |
| Cat (NM_001145510) | 87.8 | - | 76.7 | 74.5 | 72.1 | 72.5 | 65.3 | 64.7 |
| Cattle (AB510901) | 77.1 | 76.6 | - | 80.0 | 74.9 | 75.1 | 66.6 | 67.6 |
| Pig (NM_001204379) | 76.4 | 75.7 | 79.9 | - | 76.8 | 77.0 | 69.8 | 71.2 |
| Human (NM_005018) | 75.7 | 73.3 | 72.9 | 71.9 | - | 95.8 | 71.4 | 72.0 |
| Rhesus monkey (NM_001114358) | 75.7 | 73.6 | 73.6 | 72.6 | 98.3 | - | 71.3 | 71.9 |
| Mouse (NM_008798) | 68.4 | 64.2 | 65.6 | 67.4 | 71.5 | 72.6 | - | 91.3 |
| Rat (NM_001106927) | 69.4 | 65.9 | 68.3 | 70.1 | 71.2 | 72.2 | 90.3 | - |
Upper section; similarities in nucleotide level, Lower section; similarities in amino acid level. Genbank accession numbers are shown in the Table.