Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
A signal sequence is a short peptide chain that directs the transport of a newly synthesized protein to its specific location within or outside the cell. It is typically found at the beginning (N-terminus) of the protein.
5 Must Know Facts For Your Next Test
Signal sequences are usually composed of 15-30 amino acids.
They are recognized by signal recognition particles (SRPs) during translation.
The presence of a signal sequence targets proteins to the endoplasmic reticulum in eukaryotic cells.
After guiding the protein to its destination, signal sequences are often cleaved off by specific peptidases.
Mutations in the signal sequence can lead to mislocalization and dysfunction of proteins.
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Related terms
Signal Recognition Particle (SRP): A ribonucleoprotein that recognizes and binds to the signal sequence, pausing translation and targeting the ribosome-protein complex to the ER.
Endoplasmic Reticulum (ER): An organelle involved in protein and lipid synthesis; it plays a key role in correctly folding and modifying proteins.
Peptidase: An enzyme that cleaves peptide bonds, including those found in signal sequences once they have fulfilled their role.