Maclura pomifera agglutinin or lectin (MPA/MPL) is tetrameric plant protein purified by fractionation. MPA has a molecular weight of about 44,000 and consists of four subunits. It has an isoelectric point between pH 4.8 and pH 5.3, and blood group specificity towards A, B, and O (-SA). This lectin has a high affinity for tumor-associated T-antigen disaccharide (GalÎ²1,3GalNAcÎ±) and many O-linked glycopeptide structures. The structure of GalÎ²1,3GalNAcÎ± occurs on the surface of tumor cells as a mucin-associated antigenic marker, termed as T-antigen. It is also the central element in O-linked glycopeptide structures on other mammalian glycoproteins.Alkaline phosphatase (AP) is conjugated to Maclura pomifera Lectin (MPL/MPA) to show the binding of MPL/MPA in many applications including Western blotting and ELISA. Alkaline phosphatase is a large protein (140 kDa) that catalyzes the hydrolysis of phosphate groups from a substrate resulting in a colored or fluorescent product. The optimal enzymatic activity of this protein is between pH 8 and 10, and its reaction rate remains linear, improving sensitivity over time.