lectin Any of a group of proteins found in plants, animals, fungi, algae, and bacteria that share the property of binding to specific carbohydrate groups. Hence, lectins derived from plant seeds, such as concanavalin A, can cause cells to clump together by forming cross links between the oligosaccharide groups on cell surfaces. Lectins are widely used for diagnosis and experimental purposes, e.g. to identify mutant cells in cell cultures, to determine blood groups by triggering agglutination of red blood cells, or in mapping the surface of cell membranes. The role of lectins in plants remains unclear. They are especially abundant in seeds, in which they may inhibit the growth of fungi or other pathogens. In legumes it is thought that lectins take part in the recognition of suitable bacterial partners for the plant in establishing root nodule symbioses.

lectin A generic name for proteins extracted from some molluscs, fish, and plants (especially legumes), that exhibit antibody activity by effecting the agglutination of red blood cells. Some are mitogenic, while others are capable of causing the preferential agglutination of cancer cells.

lectin A generic term for proteins extracted from plants (especially legumes), and also from some molluscs and fish, that exhibit antibody activity in animals.