Plant protoplast agglutination and membrane-bound beta-lectins.

Plant protoplast agglutination caused by normal and immune serum and by artificial carbohydrate antigens is described. Evidence is presented that the new class of lectins, called all-beta lectins by previous authors, are present in protoplast membranes and responsible for both forms of agglutination. Some non-specific serum component and the artificial antigens are the 2 respective passive 'bridge' molecules between agglutinating protoplasts.