TypIVKollagen

Typ IV Kollagen, commonly referred to in English as type IV collagen, is a non-fibrillar collagen that forms a major component of basement membranes. Unlike fibrillar collagens, type IV collagen assembles into a sheet-like network that provides structural support to tissues and contributes to filtration and signaling processes within the extracellular matrix. It is encoded by six genes, COL4A1 through COL4A6, which produce multiple alpha chains (α1–α6). These chains assemble into protomers and network-forming trimers, including α1α1α2, α3α4α5, and α5α5α6, which are secreted by epithelial and endothelial cells and subsequently organize into basement membranes in a tissue-specific manner.

Type IV collagen interacts with other basement membrane components such as laminins, nidogens, and proteoglycans to form a cross-linked matrix that supports mechanical stability and selective permeability. This network is particularly important in the glomerular basement membrane of the kidney, the lens capsule of the eye, and vascular and alveolar membranes.

Genetic mutations in COL4A3, COL4A4, or COL4A5 are associated with inherited basement membrane disorders, notably Alport syndrome, which is characterized by hematuria, progressive renal failure, hearing loss, and ocular abnormalities, and thinner basement membranes observed in thin basement membrane nephropathy (TBMN). Autoantibodies directed against the NC1 domain of the α3 chain can cause Goodpasture syndrome, affecting lungs and kidneys.

In summary, Typ IV Kollagen is a essential network-forming collagen of basement membranes, supporting tissue integrity and selective filtration, with significant implications for renal, ocular, and auditory physiology and pathology.