tsüstatiini

Cystatin is a protein that functions as a cysteine protease inhibitor. These inhibitors are found in various body fluids and tissues and play a crucial role in regulating the activity of cysteine proteases. Cysteine proteases are a family of enzymes involved in a wide range of physiological and pathological processes, including protein degradation, apoptosis, and immune responses. By binding to and inactivating these proteases, cystatins help to prevent their uncontrolled activity, which could otherwise lead to cellular damage or disease.

There are several families of cystatins, classified based on their structural similarities. Cystatins are broadly divided into stefins, cystatins, and kininogens. Each family possesses distinct characteristics and distributions within the body. For example, stefins are primarily intracellular, while cystatins are found in extracellular fluids and can also be intracellular. Kininogens are larger proteins that have dual functions, acting as both protease inhibitors and precursors to bradykinin, a potent vasodilator.

The biological significance of cystatins is underscored by their involvement in various health conditions. Dysregulation of cystatin levels or activity has been linked to diseases such as cancer, neurodegenerative disorders, and inflammatory conditions. Research into cystatins continues to explore their therapeutic potential as targets for drug development aimed at modulating protease activity in these diseases. Their presence in biological samples also makes them useful biomarkers for certain medical conditions.