Scleroprotein Scleroprotein Scleroproteins or fibrous proteins constitute one of the three main types of proteins (alongside globular and membrane proteins). There are many scleroprotein superfamilies including keratin, collagen, elastin, and fibroin. The roles of such proteins include protection and support, forming connective tissue, tendons, bone matrices, and muscle fiber. A scleroprotein forms long protein filaments, which are shaped like rods or wires. Scleroproteins are structural proteins or storage proteins that are typically inert and water-insoluble. A scleroprotein occurs as an aggregate due to hydrophobic side chains that protrude from the molecule. A scleroprotein's peptide sequence often has limited residues with repeats;
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