Plant annexins function as either calcium-dependent or -independent
phospholipid binding proteins. They make up about 0.1% of total cellular
proteins. In the past, there were reports made about annexins alleviating
oxidative stress and protecting plant cells. However, these multifunctional
proteins are still insufficiently characterized in vivo.

The recently discovered Brassica juncea annexin-3 (AnnBj3) was investigated
through Arabidopsis thaliana plants expressing AnnBj3 to study its possible
function in oxidative stress response. Results suggested that AnnBj3
relieved oxidative stress by protecting the photosynthesis and plasma
membrane from methyl viologen-mediated damage. AnnBj3 detoxifies hydrogen
peroxide and also exhibited antioxidative properties in vitro.

The protein also increased total peroxidase activity in transgenics and
interfered with other cellular antioxidants. This interaction between the
protein and the antioxidants gave an overall cellular protection against
methyl viologen-induced cytotoxicity.

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