Signal peptide

Signal Peptide

A Signal peptide (or signal sequence, leader sequence, leader peptide) is a short (3-60 amino acids long) peptide chain that directs the post-translational transport of a protein.

Function

Signal peptides are used to direct the protein to certain locations within the cell. They are usually found at the N-terminus of the protein sequence and are cleaved off by a signal peptidase after the protein is transported.

Structure

The structure of a signal peptide varies between different proteins, but they generally contain three regions: a positively charged n-region, a hydrophobic h-region, and a polar c-region.

Signal Recognition Particle

The Signal Recognition Particle (SRP) is a protein-RNA complex that recognizes and targets specific proteins to the endoplasmic reticulum in eukaryotes and the plasma membrane in prokaryotes.

Secretory Proteins

Secretory proteins are synthesized on ribosomes bound to the ER. They have signal peptides that direct them into the ER lumen, where they are folded and modified.

See Also

• Protein targeting
• Protein biosynthesis
• Post-translational modification