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The AAUAAA signal is a six-nucleotide RNA sequence involved in cleavage and polyadenylation of many eukaryotic pre-mRNAs. Recognition of the signal helps organize processing downstream, after which a poly(A) tail is added. The signal itself is an encoded part of the RNA; the tail is subsequently synthesized and is not simply a copied run of genomic adenines. ^[ref]

Mutating the signal and comparing processing of defined RNA substrates supplied a direct functional test. The result concerns a particular processing context: other surrounding sequences and protein factors also contribute, and biological polyadenylation sites can use signal variants. Sequence recognition, cleavage position and final tail length are separate features of the mature transcript.

Researcher in RNA processing. Zarkower and collaborators investigated the requirement for the AAUAAA signal sequence in transcript cleavage and polyadenylation, connecting a short RNA signal with formation of a mature transcript end.^[ref]