The Nk1 gene family is named after Drosophila NK1, also known as slouch (slou), which is part of the NK homeobox gene cluster (Jagla et al. 2001). There are two Nk1 genes in human, on different chromosomes, generated by genome duplication at the base of the vertebrates. Amphioxus also has two Nk1 genes, but these were generated by tandem duplication (Luke et al. 2001). The NK gene cluster is broken in chordates (Luke et al. 2001).|
Jagla K, Bellard M, Frasch M (2001) BioEssays 23: 125-133.
Luke GN et al. (2001) PNAS 100:5292-5295.