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Ultrabithorax
 
 
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Ultrabithorax or Ubx is a member of the homeobox
Homeobox

A homeobox is a DNA sequence found within genes that are involved in the regulation of patterns of development in animals, fungus and plants. Genes that have a homeobox are called homeobox genes and form the homeobox gene family....
 gene family. In Drosophila melanogaster
Drosophila melanogaster

Drosophila melanogaster is a two-winged insect that belongs to the Diptera, the Order of the Fly. The species is commonly known as the Drosophilidae or vinegar fly, and is one of the most commonly used model organisms in biology, including studies in genetics, physiology and Life history theory....
 it is expressed in the third thoracic (T3) and first abdominal (A1) segments and represses wing formation. The Ubx gene regulates the decisions regarding the number of wings and legs the adult Drosophila melanogaster will have. Ubx is activated when there is a certain amount of Hunchback protein, which is a product of a gap gene
Gap gene

A gap gene encodes transcription factors in a developing embryo. They fall under the class of segmentation genes that are expressed during embryo morphogenesis....
.






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Ultrabithorax or Ubx is a member of the homeobox
Homeobox

A homeobox is a DNA sequence found within genes that are involved in the regulation of patterns of development in animals, fungus and plants. Genes that have a homeobox are called homeobox genes and form the homeobox gene family....
 gene family. In Drosophila melanogaster
Drosophila melanogaster

Drosophila melanogaster is a two-winged insect that belongs to the Diptera, the Order of the Fly. The species is commonly known as the Drosophilidae or vinegar fly, and is one of the most commonly used model organisms in biology, including studies in genetics, physiology and Life history theory....
 it is expressed in the third thoracic (T3) and first abdominal (A1) segments and represses wing formation. The Ubx gene regulates the decisions regarding the number of wings and legs the adult Drosophila melanogaster will have. Ubx is activated when there is a certain amount of Hunchback protein, which is a product of a gap gene
Gap gene

A gap gene encodes transcription factors in a developing embryo. They fall under the class of segmentation genes that are expressed during embryo morphogenesis....
. The concentrations of Hunchback only exist in the middle region of the embryo, therefore Ubx is expressed only in these segments as well.

Ubx is coded for by a 5' exon, two micro-exons, an optional B element, and a C terminal exon. The Ubx genomic DNA length is 76 kb and it's cDNA clone length is 3.2 to 4.6 kb. The 5' exon contains the 5'UTR which has 964 bases. The C terminal exon contains the 3'UTR which has 1580 to 2212 bases.

Ubx represses selected Dpp target genes in the anterior and posterior axis. Ubx represses Wingless in the posterior compartment of the dorsoventral axis. Ubx also selectively represses one enhancer of the vestigial genes in the proximodistal axis.

Mutations of the Ubx gene will lead to transformation of dorsal and ventral appendages of the third thoracic segment(T3), which includes the haltere and third leg, into the counterparts on the second thoracic segment(T2). If Ubx is present in T3, it will prevent the original fate of the T2 segment. Such mutations can produce a second set of wings.

The developmental role of Ubx is determined by the splicing that takes place during development. Certain splice factors of a particular cell allow that cell to regulate the developmental fate of that cell by making different splice variants of transcription factors.

Alternate splicing of the Ubx transcript produces a family of five proteins, called Ubx isoforms. These proteins function as transcription factors.