Serpin is the name given to a superfamily of proteins that all share a similar structure. These are found in virtually all forms of life and are known for their protease inhibition activities. These irreversible activities lead to a conformational change in its target site.
A Serpin’s protease inhibition is involved in a range of biological processes, such as inflammation and coagulation. Typically, the inhibition will control these processes, which has led to the proteins being the focus of extensive research.
Most of these proteins control proteolytic cascades, although some don't. Instead, some perform storage, among other duties.
While Serpins all have different functions, they share the same basic structure. They each have three β-sheets, alongside either eight or nine α-helices. The most prominent parts of the structure are its A sheet and its reactive centre loop.
That’s driven by the A sheet’s dual β-strands, alongside the RCL’s initial interaction with the target protease.
Serpin Function & Localization
The majority of Serpins focus on extracellular roles. They are, for example, responsible for tissue remodelling and inflammatory and immune responses in the bloodstream. By inhibiting certain proteases, they can also affect development.
The exact target and function of these intracellular processes can be difficult to determine, as some molecules often have overlapping duties. Typically, however, they protect against any inappropriate proteases within the cell.
Serpins can also perform a range of non-inhibitory roles. These include the transport of multiple other hormones and molecules, such as cortisol and thyroxine. These roles can often differ from species to species, with birds often seeing slightly different effects than humans.