Table 2.

Motifs which regulate heterotypic compatibility

Group 1 – K-N type
Consensus -Φ(K/R)CxxxPCPNxVDCΩΨS-
Cx26	167 – VKCNAWPCPNTVDCFVS – 183
Cx30	167 – LKCGIDPCPNLVDCFIS – 183
Cx32	166 – VKCDVYPCPNTVDCFVS – 182
Cx46	179 – YRCDRWPCPNTVDCFIS – 195
Cx50	181 – YRCSRWPCPNVVDCFVS – 197
Group 1 – Other
Cx31	162 – VQCANVAPCPNIVDCYIA – 179
Group 2 – H type
Consensus -ΦxCxxxPCPHxVDCΩΨS-
Cx30.3	162 – VACSVEPCPHTVDCYIS – 178
Cx31.9	164 – FACAGPPCPHTVDCFVS – 182
Cx43	185 – YTCKRDPCPHQVDCFLS – 201
Cx45	207 – YVCSRLPCPHKIDCFIS – 223
Cx47	240 – FPCSRQPCPHVVDCFVS – 256
Cx40	183 – HVCRRSPCPHPVNCYVS – 199
Group 2 – Other
Cx37	185 – FVCQRAPCPYLVDCFVS – 201
Cx36	229 – YECNRYPCIKEVECYVS – 245

Shown are motifs in the second extracellular loop (EL2) domain that help confer heterotypic specificity. Group 1 and Group 2 designations are from [28]. The consensus amino acid sequences for K-N and H type EL2 domains are also shown, where Φ (refers to hydrophobic residues, Ω refers to aromatic residues, and Ψ refers to amino acids with large aliphatic side chains [105]. Cx31, Cx36 and Cx37 do not fit well in either the K-N or H type categories. Note that aside from a few key residues (underlined, bold), the K-N and H type consensus sequences are comparable. See also Figure 2.