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ANTP Class
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Nk4 Family
The Nk4 or tin gene family is named after the NK4 or tinman (tin) gene in Drosophila, which is part of the NK or 93DE homeobox gene cluster (Jagla et al. 2001). In humans, there are three Nk4 genes (NKX2-3, NKX2-5, NKX2-6), on different chromosomes, generated by genome duplication at the base of the vertebrates. Amphioxus has a single Nk4 gene (AmphiNK2-tin). The NK gene cluster has broken in chordates (Luke et al. 2001). Nk4 genes are usually physically adjacent to Nk3 (bap) genes.

The nomenclature of Nk4 genes is very confusing, as they have often the prefix NK2 instead of NK4 (this erroneous situation arose because the Drosophila NK4 (tin) gene is divergent and its true orthologues are not readily recognized by simple sequence comparison). The human genome has seven genes with the prefix NK2; these divide into three distinct gene families as follows: NKX2-1 and NKX2-4 form the Nk2-1 family (with the Drosophila gene scro), NKX2-2 and NKX2-8 form the Nk2-2 family (with the Drosophila gene vnd), NKX2-3, NKX2-5 and NKX2-6 form the NK4 gene family (with the Drosophila gene tin). Renaming the Nk4 genes, for example to CSX1, CSX2, CSX3, would help to simplify the nomenclature.

Holland PWH, Booth HAF, Bruford EA (2007) BMC Biology 5:47.
Families List of Class ANTP :
HOXL subclass
NKL subclass
Loci in Nk4 of Frog back to top..
nkx2-3NK2 transcription factor related, locus 3Nk4Frog 
nkx2-5NK2 transcription factor related, locus 5Nk4Frog 
nkx2-6NK2 transcription factor related, locus 6Nk4Frog