Immunoglobulin A only weakly. IgA exists in two isotypes, IgA1 and IgA2. They are both heavily glycosylated proteins. While IgA1 predominates in serum (~80%), IgA2 percentages are higher in secretions than in serum (~35% in secretions); the ratio of IgA1 and IgA2 secreting cells varies in the different lymphoid tissues of the human body: Both IgA1 and IgA2 have been found in external secretions like colostrum, maternal milk, tears and saliva, where IgA2 is more prominent than in the blood. Polysaccharide antigens tend to induce more IgA2 than protein antigens. Both IgA1 and IgA2 can be in membrane-bound form. ("see B-cell receptor")
History of sonata form History of sonata form Sonata form is one of the most influential ideas in the history of Western classical music. Since the establishment of the practice by composers like C.P.E. Bach, Haydn, Mozart, Beethoven, and Schubert and the codification of this practice into teaching and theory, the practice of writing works in sonata form has changed considerably. Properly speaking, sonata form did not exist in the Baroque period; however, the forms which led to the standard definition did. In fact, there is a greater variety of harmonic patterns in Baroque works called "sonatas" than in the Classical period. The sonatas