Alpha-keratin keratin cell due to their effect on the various hydrogen bonds in the alpha-keratin network. Alpha-keratins proteins can be one of two types: type I or type II. There are 54 keratin genes in humans, 28 of which code for type I, and 26 for type II. Type I proteins are acidic, meaning they contain more acidic amino acids, such as aspartic acid, while type II proteins are basic, meaning they contain more basic amino acids, such as lysine. This differentiation is especially important in alpha-keratins because in the synthesis of its sub-unit dimer, the coiled coil, one protein coil
Alpha-keratin must be type I, while the other must be type II. Even within type I and II, there are acidic and basic keratins that are particularly complementary within each organism. For example, in human skin, K5, a type II alpha keratin, pairs primarily with K14, a type I alpha-keratin, to form the alpha-keratin complex of the epidermis layer of cells in the skin. Hard alpha-keratins, such as those found in nails, have a higher cysteine content in their primary structure. This causes an increase in disulfide bonds that are able to stabilize the keratin structure, allowing it to resist a