Lectin Lectin Lectins are carbohydrate-binding proteins, macromolecules that are highly specific for sugar moieties of other molecules. Lectins perform recognition on the cellular and molecular level and play numerous roles in biological recognition phenomena involving cells, carbohydrates, and proteins. Lectins also mediate attachment and binding of bacteria and viruses to their intended targets. Lectins are ubiquitous in nature and are found in many foods. Some foods such as beans and grains need to be cooked or fermented to reduce lectin content. Some lectins are beneficial, such as CLEC11A which promotes bone growth, while others may be powerful toxins such as ricin.
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