The Structure of Concanavalin A at 4 A Resolution

Concanavalin A (Con A) is a phytohemagglutinin obtained from the jack bean, Canavalia ensiformis, and first purified and crystallized by Sumner (1919). This protein agglutinates a variety of cell types (Sumner and Howell, 1935, 1936a), induces mitosis and blast transformation in lymphocytes (Rieke, 1969; Beckert and Sharkey, 1970; Powell and Leon, 1970), and inhibits the growth of mouse myelomas in vivo (Shoham et al., 1970). Certain cell lines transformed by polyoma virus contain 23−58 × 103 receptor sites for Con A per cell, whereas the untransformed cells contain only 4−8 × 103 sites (Inbar and Sachs, 1969a, b). However, trypsinization of the normal cells reveals nearly as many receptor sites as are present on transformed cells (ibid). Furthermore, Con A which has been treated with trypsin restores normal growth patterns to transformed mouse 3T3 cells (Burger and Noonan, 1970).