proteins that share the common characteristic of binding to carbohydrates. Some antibodies and carbohydrate-metabolizing proteins (enzymes) also bind to carbohydrates, however they are not considered lectins. plant lectins are carbohydrate-binding proteins that have been primarily identified by their hemagglutinating activity (hemagglutinins). However, a variety of lectins occur in animal species where they serve diverse array of functions through specific carbohydrate recognition.