Signal Peptide

What's signal peptide?

A signal peptide, sometimes referred to as signal sequence, targeting signal, localization signal, localization sequence, transit peptide, leader sequenceor leader peptide. It is a short peptide, usually 16-30 amino acids long. [1] It present at the N-terminus of the majority of newly synthesized proteins that are destined towards the secretory pathway. [2] These proteins include those that reside either inside certain organelles (the endoplasmic reticulum, golgi or endosomes), secreted from the cell, or inserted into most cellular membranes. Although most type I membrane-bound proteins have signal peptides, the majority of type II and multi-spanning membrane-bound proteins are targeted to the secretory pathway by their first transmembrane domain, which biochemically resembles a signal sequence except that it is not cleaved. 

The properties of the amino acids that constitute the signal peptide region of a protein are the significant factors determining interaction with the protein transport system, hence the destination to which that protein is delivered. Different classes of signal peptide are used to specify different cellular placement. It should be reiterated that not all proteins possess signalling regions; those which don’t are maintained in the cytoplasm.

Function (Translocation) of Signal peptides

Signal peptides function to prompt a cell to translocate the protein, usually to the cellular membrane. In prokaryotes, signal peptides direct the newly synthesized protein to the SecYEG protein-conducting channel, which is present in the plasma membrane. A homologous system exists in eukaryotes, where the signal peptide directs the newly synthesized protein to the Sec61 channel, which shares structural and sequence homology with SecYEG, but is present in the endoplasmic reticulum.[3] Both the SecYEG and Sec61 channels are commonly referred to as the translocon, and transit through this channel is known as translocation. While secreted proteins are threaded through the channel, transmembrane domains may diffuse across a lateral gate in the translocon to partition into the surrounding membrane.

Signal peptides determine secretion efficiency

Signal peptides are extremely heterogeneous and many prokaryotic and eukaryotic signal peptides are functionally interchangeable even between different species however the efficiency of protein secretion is strongly determined by the signal peptide.[4][5]


Please note that all peptides in online store are only for laboratory research purpose, not for human consumption. If you have any questions or inquiry, please feel free to contact the knowledgeable and experienced Giant Lab team:



  1. Kapp, Katja; Schrempf, Sabrina; Lemberg, Marius K.; Dobberstein, Bernhard (2013-01-01). Post-Targeting Functions of Signal Peptides. Landes Bioscience.
  2. ^Blobel G, Dobberstein B (Dec 1975). “Transfer of proteins across membranes. I. Presence of proteolytically processed and unprocessed nascent immunoglobulin light chains on membrane-bound ribosomes of murine myeloma”. J Cell Biol. 67 (3): 835–51. doi:1083/jcb.67.3.835PMC 2111658PMID 811671.
  3. Rapoport T. (Nov 2007). “Protein translocation across the eukaryotic endoplasmic reticulum and bacterial plasma membranes”. Nature. 450 (7170): 663–9. doi:1038/nature06384PMID 18046402.
  4. Kober L, Zehe C, Bode J (April 2013). “Optimized signal peptides for the development of high expressing CHO cell lines”. Biotechnol. Bioeng. 110 (4): 1164–73. doi:1002/bit.24776PMID 23124363.
  5. ^von Heijne G (Jul 1985). “Signal sequences: The limits of variation”. J Mol Biol. 184 (1): 99–105. doi:1016/0022-2836(85)90046-4PMID 4032478.
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