Collagen hereditary link. Collagen is one of the long, fibrous structural proteins whose functions are quite different from those of globular proteins, such as enzymes. Tough bundles of collagen called "collagen fibers" are a major component of the extracellular matrix that supports most tissues and gives cells structure from the outside, but collagen is also found inside certain cells. Collagen has great tensile strength, and is the main component of fascia, cartilage, ligaments, tendons, bone and skin. Along with elastin and soft keratin, it is responsible for skin strength and elasticity, and its degradation leads to wrinkles that accompany aging. It
Keratin 5 heterodimers are formed between specific pairs of type I (acidic) and type II (basic) keratin. K5, a type II keratin, pairs with the type I keratin K14. The coiled-coil dimers undergo stepwise assembly and combine in an antiparallel manner, forming end-to-end interactions with other coiled-coils to form large 10 nm intermediate filaments. Keratin 5 (and K14) are expressed primarily in basal keratinocytes in the epidermis, specifically in the stratified epithelium lining the skin and digestive tract. Keratin intermediate filaments make up the cytoskeletal scaffold within epithelial cells, which contributes to the cell architecture and provides the cells with the ability