Abstract
Leptin (LEP) plays a key role in the regulation of energy balance in mammals, with less well-defined roles in lower vertebrates. The existence of LEP orthologs in birds has been controversial and only recently have several avian LEP genes been reported.
Still, LEP has been assumed to be missing from the chicken (Gallus gallus) genome. Here, we identify the chicken LEP (cLEP), which shares only 25% amino acid sequence identity with its human ortholog.
However, it has considerably higher homology with avian LEPs, and phylogenetic analysis shows it as clustering with avian LEP sequences. The cLEP and the other known avian LEP sequences all have high GC content.
We argue that this property is behind the technical difficulties impeding the identification of these avian genes. The identification of cLEP can be expected to help elucidate leptin signaling pathways in wild and domestic chickens.