Fig. 3. Cornichon belongs to a conserved protein family. (A) Drosophila Cni and Cni-related, and their human homologues HsCni (gb| AAD20960.1) and HsCni4 (gb| NP_054903.1) share 21.5% identical (dark grey) and 43.9% similar (light grey) amino acids. Conservation is much higher between pairs of homologues: 66.7% identitical/85.4% similar in the case of Cni and HsCni, and 51.2% identitical/81.8% similar for Cnirel and HsCni4 (residues identical between homologues in medium grey). Conserved residues are distributed along the entire length of the proteins, predicted transmembrane domains are underlined. (B) Rootless phylogenetic tree for the fly, human and yeast Cni family members. Cnirel and human Cni4 form a distinct branch. Tree constructed by neighbour-joining, bootstrap support>98% for all nodes. (C) Model of the membrane topology predicted for Cni using TMHMM (www.cbs.dtu.dk/services/TMHMM) and TMpred (www.ch.embnet.org), with the N terminus facing the cytoplasm. The three transmembrane domains are labelled in light grey, while the Grk-binding domain (dark grey) maps to the N terminus, including the first lumenal loop. Black residues denote the conserved diaromatic motive.