Editing Alu element (section)

=== Related elements ===
B1 elements in rats and mice are similar to Alus in that they also evolved from 7SL RNA, but they only have one left monomer arm. 95% percent of human Alus are also found in chimpanzees, and 50% of B elements in mice are also found in rats. These elements are mostly found in introns and upstream regulatory elements of genes.<ref>{{cite journal |last1=Tsirigos |first1=Aristotelis |last2=Rigoutsos |first2=Isidore |last3=Stormo |first3=Gary D. |title=Alu and B1 Repeats Have Been Selectively Retained in the Upstream and Intronic Regions of Genes of Specific Functional Classes |journal=PLOS Computational Biology |date=18 December 2009 |volume=5 |issue=12 |pages=e1000610 |doi=10.1371/journal.pcbi.1000610 |pmid=20019790 |pmc=2784220|bibcode=2009PLSCB...5E0610T |doi-access=free }}</ref>

The ancestral form of Alu and B1 is the fossil Alu monomer (FAM). Free-floating forms of the left and right arms exist, termed free left Alu monomers (FLAMs) and free right Alu monomers (FRAMs) respectively.<ref>{{cite journal |last1=Kojima |first1=K. K. |title=Alu Monomer Revisited: Recent Generation of Alu Monomers |journal=Molecular Biology and Evolution |date=16 August 2010 |volume=28 |issue=1 |pages=13–15 |doi=10.1093/molbev/msq218 |pmid=20713470|doi-access=free }}</ref> A notable FLAM in primates is the [[BC200 lncRNA]].