Figure 7. Signal peptide of bovine growth hormone. The first 31 amino acids of unprocessed growth hormone are shown. The polypeptide is made in pituitary cells, and the N-terminal signal sequence binds to Signal Recognition Proteins on the cell surface, which facilitate the transport of the polypeptide outside the cell. Once outside, the polypeptide is cleaved between the 27th and 28th amino acids, forming mature growth hormone.