Cracks in the beta-can: Fluorescent proteins from Anemonia sulcata (Anthozoa, Actinaria)

We characterize two green fluorescent proteins (GFPs), an orange fluorescen t protein, and a nonfluorescent red protein isolated from the sea anemone A nemonia sulcata. The orange fluorescent protein and the red protein seem to represent two different states of the same protein. Furthermore. we descri be the cloning of a GFP and a nonfluorescent red protein. Both proteins are homologous to the GFP from Aequorea victoria. The red protein is significa ntly smaller than other GFP homologues, and the formation of a closed GFP-l ike beta -can is not possible. Nevertheless, the primary structure of the r ed protein carries all features necessary for orange fluorescence. We discu ss a type of beta -can that could be formed in a multimerization process.