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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]

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ReferencesEdit

  1. ^ Robinson, A; Austen, B (1 September 1987). "The role of topogenic sequences in the movement of proteins through membranes". Biochem. J. 246 (2): 249–261.
  2. ^ a b Gould, Sven; Waller, R; McFadden, G (June 2008). "Plastid Evolution". Annual Review of Plant Biology. 59: 491–517. doi:10.1146/annurev.arplant.59.032607.092915. PMID 18315522.
  3. ^ Lodish, Harvey (2013). Molecular Cell Biology. Macmillan Higher Education. pp. 587–588. ISBN 1-4292-3413-X.