This database contains information on piRNA clusters in human (NCBI Build37), rhesus macaque (NCBI build 1.2), mouse (NCBI Build 37) and rat (RGSC3.4). The piRNA clusters were detected using the proTRAC software and have also been published in the proTRAC paper in BMC Bioinformatics (10 January 2012). piRNA sequences were assembled from the NCBI nucleotide database. Main sources of annotated human, mouse and rat piRNA sequences are two studies from 2006:

Girard et al. A germline-specific class of small RNAs binds mammalian Piwi proteins. Nature 442 (7099), 199-202 (2006).
Lau et al. Characterization of the piRNA complex from rat testes. Science 313 (5785), 363-367 (2006).

piRNA sequences from Macaca mulatta were obtained by 454-NGS in the course of the development of the proTRAC software.

If you use the information provided by piRNA cluster - database please cite as follows:
Rosenkranz D, Zischler H. proTRAC - a software for probabilistic piRNA cluster detection, visualization and analysis. BMC Bioinformatics 2012, 13:5 doi:10.1186/1471-2105-13-5

The piRNA clusters can be browsed separately by species (links are located on the right side of this page). Each piRNA cluster is annotated with an image that displays its topology and some additional statistical information. Furthermore, a FASTA file that contains all piRNA sequences of the given cluster is downloadable. Alternatively you can download all clusters (images and/or FASTA files) of the desired species in a zip-compressed folder (see below).

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piRNA cluster images (png format)

piRNA cluster FASTA files

How piRNAs safeguard the genome from the threat of transposable elements:

piRNA clusters are assumed to be transcribed into long single stranded precursors that are subject to subsequent processing, leading to mature piRNAs. In a process referred to as ping pong cycle (see above), piRNA guided Piwi proteins cleave transcripts of transposable elements (TEs) such as SINEs thus producing a second population of TE derived piRNAs. These piRNAs in turn can guide Piwi proteins to primary cluster transcripts to ensure the ongoing production of TE complementary piRNAs.