This web portal is dedicated to putatively active LINE-1 elements.

What are LINE-1s?

LINE-1 (Long Interspersed Nucleotide Element 1, L1) are the only autonomous retrotransposons in the group of non-LTR retrotransposons. They comprise about 18%-20% of mammalian genomes.

Click here for background information and literature on LINE-1 elements.

L1Base 2

L1Base 2 is a dedicated database containing putatively active LINE-1 (L1) insertions residing in human and rodent genomes: a) intact in the two ORFs, full length L1s (FLI-L1s) and b) L1s with intact ORF2 but disrupted ORF1 (ORF2-L1s). In addition, due to their regulatory potential, full length non-intact L1s (FLnI-L1s) were also included in the database.


A web interface to the tool for identification and functional annotation of full length L1 insertions, L1Xplorer, has been linked to the site.

Publications involving L1Base