The core of the signal peptide contains a long stretch of hydrophobic amino acids (about 5-16 residues long) that has a tendency to form a single alpha-helix and is also referred to as the "h-region".
The core of the signal peptide contains a long stretch of hydrophobic amino acids (about 5-16 residues long) Lukas Käll, Anders Krogh 2 and Erik L. L. Sonnhammer. J. Mol. Biol. (2004) 338,1027--1036 that has a tendency to form a single alpha-helix and is also referred to as the "h-region".