A repetitive sequence found in many but not all subtelomeric regions, the Y' element is located next to the telomeric repeats, or adjacent X element combinatorial repeats, either as a single copy or tandem repeat of two to four copies. Two types of Y' elements are known, Y'-L and Y'-S, and any particular array will consist of only one type, not a combination of both. Y' elements contain helicase-encoding ORFs which are expressed only during meiosis and in telomerase-deficient cells. Possible functions include rescue of telomeres when the telomeric repeats are no longer present and a role in telomere maintenance during meiosis.

This definition is in context to Yeast Genome. See more contextual defintions for Y' element.