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PRD Class
Families List  Genes List
The PRD class is the second largest of the homeobox gene classes in animal genomes; like the ANTP class these genes have only been found in animals. The PRD class derives its name from (but is not an abbreviation for) the Paired (Prd) gene of Drosophila. PRD class genes are defined phylogenetically - they form a robust monophyletic group in evolutionary trees of homeodomain sequences. The PRD homeobox class overlaps with the Pax gene class - some but not all Pax genes are in the PRD homeobox gene class, while the vast majority of PRD class homeobox genes are not Pax genes.

There are 9 Pax genes in the human or mouse genomes, defined by presence of a 128 amino acid Paired domain, and of these 7 are members of the PRD homeobox class by virtue of possessing a homeobox: complete homeobox for PAX3, 4, 6 and 7; partial homeobox for PAX2, 5 and 8 (the two human Pax genes lacking a homeobox entirely are PAX1 and PAX9; these are not included in this database). In addition to these 7 homeobox-containing Pax genes, there are a further 43 PRD class genes in the human genome. These 50 genes can be divided into 31 gene families. There are also 24 human pseudogenes generated from these genes, plus an unknown number of DUX repetitive sequences (Holland et al. 2007).

In amphioxus there are 5 Pax genes, and of these 3 are have a partial or complete homeobox (Pax-1/9 and Pon are the two lacking homeobox sequence and therefore excluded; Pon is present in Drosophila and amphioxus, but not human). In addition to these genes, there are a further 27 PRD class genes in amphioxus (Takatori et al. 2008).

Reference(s):
Holland PWH, Booth HAF, Bruford EA (2007) BMC Biology 5:47.
Takatori N et al (2008) Dev Genes Evol 218: 579-590.
 
Families List of Class PRD :
Alx(2)Arx(2)Dmbx(1)Drgx(1)Gsc(1)Hesx(1)Hopx(1)Isx(1)Nobox(1)
Otp(3)Otx(3)Pax2/5/8(1)Pax3/7(1)Pax4/6(3)Phox(2)Pitx(3)Prrx(2)Rax(2)
Shox(2)Uncx(2)Vsx(2)       
 
Loci in PRD of Frog back to top..
Symbol/LocusNameFamilyOrganismRegulator
alx1ALX homeobox 1 AlxFrog 
alx4ALX homeobox 4 AlxFrog 
arxaristaless related homeobox ArxFrog 
arx-larx likeArxFrog 
crxcone-rod homeobox OtxFrog 
dmbx1diencephalon/mesencephalon homeobox 1 DmbxFrog 
drgxdorsal root ganglia homeoboxDrgxFrog 
gscgoosecoid homeoboxGscFrog 
hesx1HESX homeobox 1HesxFrog 
hopxHOP homeoboxHopxFrog 
isxintestine-specific homeoboxIsxFrog 
nobox-lnobox likeNoboxFrog 
otp-l OtpFrog 
otpa OtpFrog 
otpborthopedia homeobox OtpFrog 
otx1orthodenticle homeobox 1 OtxFrog 
otx2orthodenticle homeobox 2OtxFrog 
pax2 Pax2/5/8Frog 
pax4lpax4 homeobox likePax4/6Frog 
pax6paired box 6Pax4/6Frog 
pax6lpaired box 6 likePax4/6Frog 
pax7paired box 7Pax3/7Frog 
phox2apaired-like homeobox 2aPhoxFrog 
phox2bpaired-like homeobox 2b PhoxFrog 
pitx1paired-like homeodomain 1 PitxFrog 
pitx2paired-like homeodomain 2 PitxFrog 
pitx2b PitxFrog 
prrx1bpaired related homeobox 1PrrxFrog 
prrx2paired related homeobox 2 PrrxFrog 
raxretina and anterior neural fold homeobox RaxFrog 
rax2 retina and anterior neural fold homeobox 2 RaxFrog 
shoxshort stature homeobox ShoxFrog 
shox2short stature homeobox 2 ShoxFrog 
uncx1UNC homeobox 1UncxFrog 
uncx2UNC homeobox 2UncxFrog 
vsx1visual system homeobox 1VsxFrog 
vsx2visual system homeobox 2VsxFrog