When an enzyme isn't just an enzyme anymore

In this issue (pages 1425-1440) Bross et al. provide evidence of surprising alternative functions for two isoforms of the plastid enzyme arogenate dehydratase. This study points to a previously unsuspected connection between central metabolism and chloroplast division and a potential new mechanism for retrograde signaling. These findings add to a growing awareness of the complexities of protein function that has substantial implications for both basic and applied plant science.