Collagen type IV is the most abundant structural component of the basement membrane, a specialized extracellular matrix, that supports epithelial and endothelial cells and separates tissues from their surrounding environments. Collagen type IV consists of polypeptide chains derived from six different alpha chains that assemble into three different collagen type IV isoforms. Unlike fibrillar collagens, collagen IV forms flexible, sheet-like networks that provide structural stability and interact with other basement membrane components, including laminins, nidogens, and proteoglycans (1,2).
The principal functions of collagen IV are to provide mechanical support, maintain basement membrane integrity, regulate cell adhesion, and contribute to tissue organization and cellular signaling. Through its interactions with cell-surface receptors and other extracellular matrix proteins, collagen IV also influences cellular behavior and tissue homeostasis (1).
Dysregulation of collagen IV is associated with several important diseases. Pathogenic variants can cause e.g. diabetic nephropathy, Alport syndrome, and cerebral small-vessel disease as well as increasing the risk of intracerebral hemorrhage and other neurological manifestations (2,3).
