In Biology, What Is a Consensus Sequence?

The Alu repeat is a member of the SINE family in the mammalian genome, with approximately 500,000 copies. In other words, there is an Alu sequence in an average of 4-6 kb. Since this DNA sequence has the recognition sequence AGCT of the restriction endonuclease AluI, it is called an Alu repeat. The typical human genome Alu sequence is 282 bp long and consists of two homologous but different subunits. The subunit is derived from the 7SLRNA gene with deletion mutations and point mutations. The two subunits are linked by adenine nucleotide-dense sequences. The unrelated 31 bp insert in the right subunit is called IH. The Alu sequence has a forward repeat at each end and a poly (A) tail at the end.

ALU

(Sequences in biology)

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It is not clear why there are so many duplicate copies of DNA sequences in the mammalian genome. It has been found that a 14 bp segment in the Alu sequence is almost identical to the replication initiation sequence of papova virus such as SV40 virus and hepatitis B virus. This suggests that the Alu sequence may be related to the origin of replication in the eukaryotic genome, but this is also controversial. This is because the number of copies of the Alu repeat is tens of times greater than expected from the origin of replication. In addition, it was found that some members of the Alu-equivalent family of Chinese hamsters, when located near other transcription units, can be transcribed into individual RNA molecules in vivo.