Signal Peptide Structure
The core of the signal peptide contains a long stretch of hydrophobic amino acids that has a tendency to form a single alpha-helix. In addition, many signal peptides begin with a short positively charged stretch of amino acids, which may help to enforce proper topology of the polypeptide during translocation by what is known as the positive-inside rule. At the end of the signal peptide there is typically a stretch of amino acids that is recognized and cleaved by signal peptidase. However this cleavage site is absent from transmembrane-domains that serve as signal peptides, which are sometimes referred to as signal anchor sequences. Signal peptidase may cleave during, or after completion of, translocation to generate a free signal peptide and a mature protein. The free signal peptides are then digested by specific proteases.
Read more about this topic: Signal Peptide
Famous quotes containing the words signal and/or structure:
“Perhaps having built a barricade when you’re sixteen provides you with a sort of safety rail. If you’ve once taken part in building one, even inadvertently, doesn’t its usually latent image reappear like a warning signal whenever you’re tempted to join the police, or support any manifestation of Law and Order?”
—Jean Genet (1910–1986)
“What is the most rigorous law of our being? Growth. No smallest atom of our moral, mental, or physical structure can stand still a year. It grows—it must grow; nothing can prevent it.”
—Mark Twain [Samuel Langhorne Clemens] (1835–1910)