The ELO family consist of eukaryotic integral membrane proteins involved in fatty acid elongation. This family consist of:

• Mammalian proteins ELOVL1 to ELOVL4 [1]. These proteins all seem to be involved in the synthesis of very long chain fatty acids.
• Yeast ELO1, ELO2 and ELO3 [2]. They seem to be components of membrane-bound fatty acid elongation systems.
• Caenorhabditis elegans hypothetical protein C40H1.4.
• Caenorhabditis elegans hypothetical protein D2024.3.

The proteins have from 271 to 435 amino acid residues. Structurally, they seem to be formed of three sections: a N-terminal region with two transmembrane domains, a central hydrophilic loop and a C-terminal region that contains from one to three transmembrane domains. As a signature pattern we selected a conserved region that contains three histidines. This region is located in the hydrophilic loop.