ABSTRACT
The eosinophil granule contains four cationic proteins that account for the bulk of the granule protein. Presumably, their basicity is the reason for the eosinophil’s intense avidity for the acidic dye eosin. These molecules are potent toxins for targets, such as parasites and mammalian cells, and possess numerous biological activities. The toxicity of Major Basic Protein (MBP) is neutralized by polymers of glutamic and aspartic acids, and these anionic polymers may useful as therapeutic agents for eosinophil-associated diseases. Analysis of guinea pig MBP by sodium dodecyl sulfate–polyacrylamide gel electrophoresis revealed a molecular weight of approximately 11,000 and showed that the molecule is rich in arginine and has a marked propensity to polymerize on the basis of the formation of disulfide bonds. Two types of guinea pig MBP, MBP-1 and MBP-2, have been isolated and partially sequenced. Analyses of cDNA indicated that both types show a prepro-MBP with three domains consisting of a signal peptide, an acidic proportion and mature MBP.
