Fig. 4. Xenopus Cx31 and Cx43.4 are highly related to other connexins. (A) Xenopus Cx31 (accession AY057997) has 68-69% similarity to mouse, rat and human Cx31. (B) Xenopus Cx43.4 (accession AY057998) is most related to zebrafish Cx43.4 at 69% similarity but also shows 58-59% similarity to chicken, human, mouse and dog Cx45. Characteristic features of connexins, such as four predicted transmembrane domains (red bars) and triplets of cysteine residues (yellow C), are evident.