ABSTRACT
Lipocalins are widely distributed in animals, insect and bacteria but very litde is known about plant lipocalins. The first lipocalin-like proteins reported in plants were the two key enzymes o f the xanthophyll cycle, the violaxanthin de-epoxidases and the zeaxanthin epoxidases. However, the peculiar architecture of these proteins raised doubt as of their true belonging to the lipocalin family. We recendy reported the identification and cloning of the first true plant lipocalins from wheat and Arabidopsis. The encoded proteins were named temperature-induced lipocalins and possess the three structurally-conserved regions that char acterize lipocalins. Sequence analyses revealed that these plant lipocalins share significant ho mology with three evolutionarily-related lipocalins, the mammalian apolipoprotein D, the bac terial lipocalin Blc and the insect Lazarillo protein. Data mining o f genomic databases and bioinformatic predictions revealed that plants possess two other lipocalin members: temperature-induced lipocalin-2 and chloroplastic lipocalin. Expression and regulation studies suggest that the plant lipocalins are associated with environmental stresses.
