Fatty acid elongation was examined in the cellular slime mold, Dictyostelium discoideum. Profiling of the total fatty acid content of D. discoideum indicated that fatty acid elongation is active. Orthologs of the fatty acid elongase ELO family were identified in the D. discoideum genome and the cDNA for one, eloA, was cloned and functionally characterized by expression in yeast. EloA is a highly active ELO with strict substrate Specificity for monounsaturated fatty acids, in particular 16:1(Delta 9) to produce the unusual 18:1(Delta 11) fatty acid. This is the first report on fatty acid elongation in a cellular slime mold. (C) 2008 Elsevier Inc. All rights reserved.