A signal peptide sometimes also called signal sequence, targeting signal, localization signal, localization sequence, transit peptide or leader peptide. It is a short, generally 5-30 amino acids long, peptide present at the N-terminus of most newly synthesized proteins. These proteins include those that reside either secreted from the cell, inside certain organelles (Golgi or endoplasmic reticulum), or inserted into most cellular membranes.