This family represents a conserved region approximately 150 residues long within plant violaxanthin de-epoxidase (VDE). In higher plants, violaxanthin de-epoxidase forms part of a conserved system that dissipates excess energy as heat in the light-harvesting complexes of photosystem II (PSII), thus protecting them from photo-inhibitory damage [1].

1: Molecular cloning of violaxanthin de-epoxidase from romaine lettuce and expression in Escherichia coli. Bugos RC, Yamamoto HY; Proc Natl Acad Sci U S A 1996;93:6320-6325. PMID:8692813