Plant lectins -- proteins that bind specifically with certain carbohydrates -- have become a basic biochemical tool, expecially valued in medical diagnosis. In the lab, different lectins can help identify blood types, charactize specific glycoproteins and study cell surfaces, including those of tumor cells. "They appear to be ubiquitous in the plant and animal kingdoms," says UC Davis biochemistry professor Marilynn E. Etzler, "but we don't know what these molecules do in the plants. It's a big embarrassment." Etzler, who has been studying the useful proteins for 24 years, will review her studies exploring how the structures of lectins are related to their functions. Using a variety of techniques -- including recombinant DNA technology -- Etzler is trying to understand how variations in lectins' structures affect the lectins' activities. "If you find out how something works, you can engineer it to work better," she says. Etzler will talk about her laboratory's approaches to the problem on Thursday afternoon, Aug. 29.