prosequence

A prosequence is a short chain of amino acids that is part of a larger protein and is removed by proteolysis after the protein has been synthesized. Prosequences are often found at the N-terminus of a protein, although they can also be located internally. The primary function of a prosequence is to act as a temporary tag or chaperone, ensuring that the protein folds correctly or is directed to its proper cellular location before becoming fully active.

The removal of the prosequence is a critical step in protein maturation. This process is catalyzed by specific enzymes called proteases, which cleave the polypeptide chain at a precise location, releasing the mature, functional protein. The prosequence itself is then typically degraded. In some cases, prosequences can also serve as inhibitors of the mature protein's activity until they are cleaved, providing a mechanism for regulating protein function. Examples of proteins that undergo processing via prosequences include digestive enzymes like pepsin and trypsin, and hormones such as insulin. The study of prosequences is important in understanding protein folding, cellular localization, and the regulation of biological processes.