Proteins related to St. John's Wort p27SJ, a suppressor of HIV-1 expression, are ubiquitous in plants

A St. John's Wort protein related to animal DING proteins suppresses HIV-1 expression. DING proteins were purified from various plant species. They all correspond to 40 kDa mature proteins harboring the typical DINGGG-N-terminus. DING proteins are secreted and their association with the cell wall varies according to the conditions.