A slippery sequence is a small section of codon nucleotide sequences (usually UUUAAAC) that controls the rate and chance of ribosomal frameshifting.
This allows a tRNA to shift by 1 base (−1) after it has paired with its anticodon, changing the reading frame.
[1] The frameshift occurs due to wobble pairing.
The Gibbs free energy of secondary structures downstream give a hint at how often frameshift happens.
[7] Tension on the mRNA molecule also plays a role.
Tandem slippage of 2 tRNAs at rous sarcoma virus slippery sequence. After the frameshift, new base pairings are correct at the first and second nucleotides but incorrect at wobble position.
E
,
P
, and
A
sites of the ribosome are indicated. Location of growing polypeptide chain is not indicated in image because there is not yet consensus on whether the −1 slip occurs before or after polypeptide is transferred from P-site tRNA to A-site tRNA (in this case from the Asn tRNA to the Leu tRNA).
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1
]
