The Alu family of dispersed repetitive sequences.

A family of related sequences that includes approximately 500,000 members is the most prominent short dispersed repeat family in primate and rodent DNA's. The primate sequence is approximately 300 base pairs in length and is composed of two imperfectly repeated monomer units, whereas the rodent repeat consists of only a single monomer. Properties of this repeat sequence, its flanking sequences in chromosomal DNA, and RNA's transcribed from it suggest that it may be a mobile DNA element inserted at hundreds of thousands of different chromosomal locations.