Homeotic genes
Homeotic
genes were discovered because of the fact that mutations in these genes
can cause extrordinary phenotypes. In homeotic mutants, correctly formed
body parts arise in ectopic places. Just as segmentation genes have the
function to divide the body into repeated units, the homeotic genes are
responsible for rendering these units different from each other. Every
segment follows a similar building plan. Homeotic genes regulate, for
example, whether the segment develops a haltere or a wing, by regulating
a large number of downstream genes required for the development of segment
specific structures. Accordingly, different homeotic genes are active
in different segments.
Media list
Homeotic genes..........additional
informationGenes discussed
|
Gene
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Gene product
- Domains
|
Function
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Links
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abdominal A (abd-A)
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homeodomain transcription factor - bithorax complex
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homeotic gene controls identity of abdominal segments
/ involved in subdivision of the visceral mesoderm
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Abdominal B (Abd-B)
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homeodomain transcription factor - bithorax complex
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homeotic gene required to specify the posterior abdomen
and the genitalia
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achaete (ac)
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transcription factor - basic HLH
|
proneural gene - involved in the determination of the
neural fate
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Antennapedia (Antp)
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homeodomain transcription factor - Antp complex
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homeotic gene controls identity of thoracic segments
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Deformed (Dfd)
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transcription factor - homeodomain - Antp class
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required to form a normal head
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labial (lab)
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transcription factor - homeodomain - Antp class
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involved in head and brain morphogenesis
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Notch (N)
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transmembrane receptor
|
neurogenic gene, responsible for lateral inhibition
and cell fate choices
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Serrate (Ser)
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transmembrane - EGF homolog - ligand for Notch
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involved in the induction, through Notch, of the wing
margin
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Sex combs reduced (Scr)
|
transcription factor - homeodomain - Antp class
|
required for labial and first thoracic segment
development
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spalt (salm)
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transcription factor - zinc finger - PRDII-BF1
homolog
|
a target of Dpp signaling - Spalt and Spalt-related
regulate vein-specific expression of knirps and the iroquois complex
|
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Ultrabithorax (Ubx)
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transcription factor - homeodomain - Antp class
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Mutations of Ubx result in transformation
of the dorsal and ventral appendages of the third thoracic segment
(the haltere and third leg) into their counterparts on the second
thoracic segment (wing and second leg)
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vestigial (vg)
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presumptive transcription factor - novel
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the activation of several genes in the wing field
requires Vg/Sd function, for example activation of Serum response
factor intervein promoter
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