EMBO Rep. 2006 Jan;7(1):59-65. doi:10.1038/sj.embor.7400576

Vengrova S, Dalgaard JZ.

The wild-type Schizosaccharomyces pombe mat1 imprint consists of two ribonucleotides.

The T4 DNA ligase can join 5′p to 2′OH 3′p or 2′p 3′OH nucleotides. The Taq polymerase can elongate across up to three ribonucleotides.