Probably plays an important role in the regulation of erythrocyte shape and mechanical properties. Oligomer. Interacts with the cytoplasmic domain of SLC4A1/band 3 anion transport protein. Cytoplasmic surface of erythrocyte membranes. The substitution of an Ala for a Cys in the active site may be responsible for the lack of transglutaminase activity of band 4.2. Belongs to the transglutaminase superfamily. Transglutaminase family. Was originally thought to be pallidin.