Mammalian-wide interspersed repeat

Mammalian-wide interspersed repeats (MIRs) are transposable elements in the genomes of some organisms and belong to the group of Short interspersed nuclear elements (SINEs).

Incidence

MIRs are found in all mammals (including marsupials).[1]

In human

It is estimated that there are around 368,000 MIRs in the human genome.[2]

Structure

The MIR consensus sequence is 260 basepairs long and has an A/T-rich 3' end.[1]

Propagation

Like other Short interspersed nuclear elements (SINEs), MIR elements used the machinery of LINE elements for their propagation in the genome, which took place around 130 million years ago. They cannot retrotranspose anymore since the loss of activity of the required reverse transcriptase.[3]

History of discovery

MIR elements have been first described in human genome 1989-1991 [4][5][6] and were first referred as MB1 family repeats (mirror to sequences of mouse B1 repeat). Then this family repeats were found in other mammalian genomes.[7] Then this family was renamed as "Mammalian interspersed repeats" in 1992 [8] Later this family was shown to be common for vertebrate genomes.[9]

References
  1. Smit, Arian F. A.; Riggs, Arthur D. (1995). "MIRs are classic, tRNA-derived SINEs that amplified before the mammalian radiation". Nucleic Acids Research. 23 (1): 98–102. doi:10.1093/nar/23.1.98. PMC 306635. PMID 7870595.
  2. Lander; et al. (2001). "Initial sequencing and analysis of the human genome" (PDF). Nature. 409 (6822): 860–921. Bibcode:2001Natur.409..860L. doi:10.1038/35057062. PMID 11237011.
  3. Krull, M; Petrusma, M; Makalowski, W; Brosius, J; Schmitz, J (August 2007). "Functional persistence of exonized mammalian-wide interspersed repeat elements (MIRs)". Genome Research. 17 (8): 1139–45. doi:10.1101/gr.6320607. PMC 1933517. PMID 17623809.
  4. Donehower, Lawrence A.; Slagle, Betty L.; Wilde, Margaret; Darlington, Gretchen; Butel, Janet S. (1989). "Identification of a conserved sequence in the non-coding regions of many human genes". Nucleic Acids Research. 17 (2): 699–722. doi:10.1093/nar/17.2.699. PMC 331613. PMID 2536922.
  5. Korotkov, Eugene V. (1990). "A family of mirror B1-like sequences from human genome". Dokl. Akad. Nauk SSSR (in Russian). 311 (1): 238–242. PMID 2357927.
  6. Korotkov, Eugene V. (1991). "A new family of widely propagated MB1-repeats in the human genome". Mol Biol (Mosk) (in Russian). 25 (1): 250–263. PMID 1896037.
  7. Korotkov, Eugene V. (1992). "The MB1 family of repeats in clones from the genomes of mammals". Izv Akad Nauk SSSR Biol (in Russian). Jul–Aug (4): 546–557. PMID 1452902.
  8. Jurka, Jerzy; Walichiewicz, Jolanta; Milosavljevic, Aleksandar (October 1992). "Prototypic sequences for human repetitive DNA". Journal of Molecular Evolution. 35 (4): 286–291. Bibcode:1992JMolE..35..286J. doi:10.1007/BF00161166. PMID 1404414.
  9. Korotkov, Eugene V.; Korotkova, Maria A.; Rudenko, Valentina M. (2000). "MIR--family of repeats common for vertebrate genomes". Mol Biol (Mosk) (in Russian). 34 (4): 553–559. doi:10.1007/BF02759556. PMID 11042848.
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