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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,cite-ref-robinson-role-1-0[1] and ensure they are transported to the correct organelle after synthesis.cite-ref-gould-plastid-2-0[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.cite-ref-3[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.cite-ref-gould-plastid-2-1[2]

• See also

• References

• Protein targeting

• Target peptide

• Translocon

• Signal peptide

cite-note-robinson-role-11. ↑ citerefrobinsonausten-b1987Robinson, A; Austen, B (1 September 1987). "The role of topogenic sequences in the movement of proteins through membranes". Biochem. J. 246 (2): 249–261. doi:10.1042/bj2460249. PMC 1148271. PMID 3318806.

cite-note-gould-plastid-22. ↑ citerefgouldwaller-rmcfadden-g2008Gould, 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.

cite-note-33. ↑ citereflodish2013Lodish, Harvey (2013). Molecular Cell Biology. Macmillan Higher Education. pp. 587–588. ISBN 978-1-4292-3413-9.