PROSITE documentation PDOC01042

Cornichon family signature

The Drosophila cornichon protein (gene: cni) [1] is required in the germline for dorsal-ventral signaling. The dorsal-ventral pattern formation involves a reorganization of the microtubule network correlated with the movement of the oocyte nucleus, and depending on the initial correct establishment of the anterior-posterior axis via a signal from the oocyte produced by cornichon and gurken and received by torpedo protein in the follicle cells. The biochemical function of the cornichon protein is currently not known.

It is a protein of 144 residues that seems to contain three transmembrane regions. It is evolutionary related to the following eukaryotic proteins:

• Yeast ERV14 [2], probably involved in regulation of secretory protein export.
• Human and mouse [3] cornichon proteins (gene cnih).
• Mouse cornichon-like protein (gene cnil).
• Caenorhabditis elegans hypothetical protein T09E8.3.
• Yeast hypothetical protein YBR210W.
• Schizosaccharomyces pombe hypothetical protein SpAC2C4.05.

The high conservation of this family throughout evolution suggests a role in basic cellular functions.

As a signature for these proteins we selected a conserved region located in the loop between the first and second transmembrane regions. This conserved region contains three acidic residues.