Ultrabithorax
Encyclopedia
Ultrabithorax or Ubx is a member of the homeobox
gene family. Homeobox proteins function as transcription factors
. In Drosophila melanogaster
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 lack of Hunchback protein. The concentrations of Hunchback only exist in the anterior and posterior regions of the embryo
, therefore Ubx is expressed
only in middle segments. Thus, the hb gene may play an important role in the specification of the boundaries of Ubx expression.
The Ubx gene contains a 5' exon
, two micro-exons, an optional B element, and a C terminal exon. The Ubx genomic DNA length is 76 kb and its 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.
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. In D. melanogaster, at least six different isoforms of Ubx exist.
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.
Interestingly, Ubx can also form materials in vitro besides its well known function as a transcription factor .
including regulatory genes such as transcription factors, signalling components and terminal differentiation genes.
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.
Homeobox
A homeobox is a DNA sequence found within genes that are involved in the regulation of patterns of anatomical development in animals, fungi and plants.- Discovery :...
gene family. Homeobox proteins function as transcription factors
Transcription factor
In molecular biology and genetics, a transcription factor is a protein that binds to specific DNA sequences, thereby controlling the flow of genetic information from DNA to mRNA...
. In Drosophila melanogaster
Drosophila melanogaster
Drosophila melanogaster is a species of Diptera, or the order of flies, in the family Drosophilidae. The species is known generally as the common fruit fly or vinegar fly. Starting from Charles W...
it is expressed in the third thoracic
Thorax (insect anatomy)
The thorax is the mid section of the insect body. It holds the head, legs, wings and abdomen. It is also called mesosoma in other arthropods....
(T3) and first abdominal (A1) segments
Segmentation (biology)
Segmentation in biology refers to either a type of gastrointestinal motility or the division of some animal and plant body plans into a series of repetitive segments. This article will focus on the segmentation of animal body plans, specifically using the examples of the phyla Arthropoda,...
and represses wing
Insect wing
Insects are the only group of invertebrates known to have evolved flight. Insects possess some remarkable flight characteristics and abilities, still far superior to attempts by humans to replicate their capabilities. Even our understanding of the aerodynamics of flexible, flapping wings and how...
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 lack of Hunchback protein. The concentrations of Hunchback only exist in the anterior and posterior regions of the embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
, therefore Ubx is expressed
Gene expression
Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. These products are often proteins, but in non-protein coding genes such as ribosomal RNA , transfer RNA or small nuclear RNA genes, the product is a functional RNA...
only in middle segments. Thus, the hb gene may play an important role in the specification of the boundaries of Ubx expression.
The Ubx gene contains a 5' exon
Exon
An exon is a nucleic acid sequence that is represented in the mature form of an RNA molecule either after portions of a precursor RNA have been removed by cis-splicing or when two or more precursor RNA molecules have been ligated by trans-splicing. The mature RNA molecule can be a messenger RNA...
, two micro-exons, an optional B element, and a C terminal exon. The Ubx genomic DNA length is 76 kb and its 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.
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. In D. melanogaster, at least six different isoforms of Ubx exist.
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.
Interestingly, Ubx can also form materials in vitro besides its well known function as a transcription factor .
Target genes
Ubx targets hundreds of different genes at different stages of morphogenesisMorphogenesis
Morphogenesis , is the biological process that causes an organism to develop its shape...
including regulatory genes such as transcription factors, signalling components and terminal differentiation genes.
Ubx represses
Regulation of gene expression
Gene modulation redirects here. For information on therapeutic regulation of gene expression, see therapeutic gene modulation.Regulation of gene expression includes the processes that cells and viruses use to regulate the way that the information in genes is turned into gene products...
selected Dpp
Decapentaplegic
Decapentaplegic is a key morphogen involved in the development of the fruit fly Drosophila melanogaster. It is known to be necessary for the correct patterning of the fifteen imaginal discs, which are tissues that will become limbs and other organs and structures in the adult fly. It has also been...
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.