Part of a complex with inhibitory activity, but CMb is inactive as a separate subunit. Heterotetramer of one CMa, one CMb and two CMd chains. Endosperm. Five disulfide bonds are present (Probable), which are essential for the inhibitor activity. Exists both in a glycosylated and in an unglycosylated form. The glycosylated form is a potent allergen. Causes an allergic reaction in human. Involved in baker's asthma. Belongs to the protease inhibitor I6 (cereal trypsin/alpha-amylase inhibitor) family.