Figure 3: Illustration to show the sequence segments highlighted by sliding the scaled window along a protein sequence. During the sliding process, the scales on the window are aligned with different amino acids so as to define different peptide segments. When the scale −1 is aligned with the tail residue of the signal sequence and scale aligned with the head residue of the mature protein as shown in (a), the peptide segment is seen within the window regarded as secretion cleavable. Peptide segments seen within the window for all the other cases, such as those shown in ((b) and (c)), are regarded as nonsecretion cleavable.