SERPIN gene family

Genes in the SERPIN gene superfamily provide instructions for making proteins called serine protease inhibitors or serpins. Most serpins help control certain chemical reactions by blocking (inhibiting) the function of proteins, specifically enzymes called serine proteases. A few serpins inhibit other types of proteins, and several do not have an inhibitory function.

Each serpin with an inhibitory role is responsible for blocking the activity of one or more proteins. Serpins attach (bind) to their target proteins to prevent them from completing any further reactions. Upon binding to a target, an irreversible change in the structure of a serpin protein occurs. Certain cells recognize when a serpin is bound to its target and clear these attached proteins from the bloodstream.

Researchers have identified at least 37 serpin genes in humans. These genes are divided into subgroups called clades based on various aspects of similarity. Each gene in this family is named with SERPIN, followed by a letter associated with its clade and a number assigned to the specific gene within the clade. For example, the first SERPIN gene in clade A is written as SERPINA1.

Serpin proteins are very sensitive to any changes. Mutations that alter even a single protein building block (amino acid) in critical regions of these proteins can disrupt their usual functions. Abnormal serpin proteins often form clumps (aggregates) that can build up to toxic levels within cells. These protein aggregates may also cause a shortage of the inhibitor in areas where it is needed to control chemical reactions. Disorders caused by aggregates of abnormal serpins are called serpinopathies. Mutations in the SERPIN genes can cause various disorders, including a lung disease called emphysema, hereditary angioedema, a type of familial dementia, and abnormal blood clotting (thrombosis).