Members of this family are found, exclusively in the vicinity of CRISPR repeats and other CRISPR-associated (cas) genes, in Methanothermobacter thermautotrophicus (Methanobacterium thermoformicicum), Thermus thermophilus (Deinococcus-Thermus), Chloroflexus aurantiacus (Chloroflexi), and Thermomicrobium roseum (Thermomicrobia).