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transposon (jumping gene, transposable element, mobile genetic element, selfish DNA)
Sequence of mobile DNA able to move to different positions within the genome of a single cell (transposition).
In the process of transposition, they may cause mutations &/or change the amount of DNA in the genome.
Found in all major branches of life.
Classification:
May be grouped based on their mechanism of transposition:
- retrotransposons (class 1)
- class 2 transposons (DNA transposons)
The most common form of transposon in humans is the Alu sequence
Physiology:
- may have provided a means of producing antibody diversity
- V(D)J recombination system operates by a mechanism similar to that of transposons
- evolution of autosomal retrogenes from X-linked progenitors compensates for X-chromosome silencing during male meiosis
Pathology:
- transposons are mutagens
- they can damage the genome of their host cell:
- a transposon or a retroposon that inserts itself into a functional gene will most likely disable that gene
- after a transposon leaves a gene, the resulting gap will probably not be repaired correctly
- multiple copies of the same sequence, such as Alu sequences can hinder precise chromosomal pairing during mitosis, resulting in unequal crossovers, one of the main reasons for chromosome duplication
- diseases often caused by transposons include:
- hemophilia A, hemophilia B
- severe combined immunodeficiency
- porphyria
- Duchenne muscular dystrophy
- transposons may predispose to cancer
- many transposons contain promoters which drive transcription of their own transposase; these promoters can cause aberrant expression of linked genes, causing disease or mutant phenotypes
Mechanisms adapted for reducing transposon activity include:
- gene deletion
- RNA interference (RNAi)
Transposons are used as a research tool to alter DNA inside a living organism. Transposons make up a large fraction of genome sizes of eukaryotic species (40% of human DNA) [3]
Related
gene
Specific
class 2 transposon (DNA transposon)
retrotransposon (class 1 transposon)
General
deoxyribonucleic acid (DNA)
References
- Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Transposon
- McClintock, B.
The origin and behavior of mutable loci in maize.
Proc Natl Acad Sci U S A. (1950) 36(6): 344-55.
PMID: 15430309
- Grandi N, Tramontano E.
Human Endogenous Retroviruses Are Ancient Acquired Elements
Still Shaping Innate Immune Responses.
Frontiers in Immunology, 2018. Sept 10
PMID: 30250470 PMCID: PMC6139349 Free PMC article