A topogenic sequence is a collective term used for a peptide sequence present at nascent proteins essential for their insertion and orienting in cellular membranes. The sequences are also used to translocate proteins across various intracellular membranes,[1] and ensure they are transported to the correct organelle after synthesis.[2] The position of the sequence may be at the end, e.g. N-terminal signal sequence, or in mid parts of the nascent protein, e.g. stop-transfer anchor sequences and signal-anchor sequences.[3] If the sequence is at the end of the polypeptide, it is cleaved off after entering the ER-lumen (via a translocon) by a signal peptidase, and subsequently degraded.
As an example, the vast majority of all known complex plastid preproteins (an 'unactivated' protein) encoded in the nucleus possess a topogenic sequence.[2]
See also
References
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