Fig. 3. Sequence analysis of Atlantic cod GLUT1. Amino acids are represented by the single letter code and numbered on the right. Boxes numbered with Roman numerals represent the putative 12 transmembrane helices. Residues that are highly conserved in all glucose transporters are highlighted in gray, while those that are specific to class I glucose transporters are highlighted in black. It should be noted that the PETKGR motif varies in Atlantic cod GLUT1 in that the K is substituted by an R.