Sequence alignment of zebrafish and human Nme protein domains and highlight on Nme4 specificity. (A) Nme protein domains were identified using NCBI Conserved Domain Database . Domains were aligned using MUSCLE , and graphic view was generated using BioEdit V. 7.0.9 software. Residues identified as important for kinase function catalytic mechanism are indicated by an * according to X-ray structure information on human NME2  and Lascu and Gonin review  on the catalytic mechanism of NDP Kinase. (B) Mitochondrial membrane linkage triad with central Arginine90. (C) Proline to Serine mutation restricted to tetrapods. Sequences accession numbers are listed in Tables 1 and 2.