{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% of the total protein content. Collagen I, II, III, IV, and V are the most prominent types, each type has a specific struction and function, contributing to different tissues and organs. Collagen IV is a major constituent of the basement membranes, along with laminins and enactins. It is composed of the alpha 1 IV chain and alpha 2 IV chain in a 2:1 ratio, and forms insoluble fibers with high tensile strength. Collagen IV is expressed at sites of mesenchymal elements and epithelial basal laminae."}]}]}