The major birch (Betula alba L.) pollen allergen, Bet v 1, has been sh
own to be homologous to pathogenesis-related proteins in a number of p
lants. Recently, it was demonstrated that a ginseng protein with high
homology to an intracellular pathogenesis-related protein of parsley a
nd to Bet v 1 is a ribonuclease (RNase). Birch pollen extract was sepa
rated in an RNase activity gel. Four major RNase bands were excised fr
om the gel, reseparated by sodium dodecyl sulfate-polyacrylamide gel e
lectrophoresis and identified by Western blotting with a specific Bet
v 1 monoclonal antibody and patient's serum. Thus the monomer and the
dimer of Bet v 1 showed RNase activity. Purified recombinant Bet v 1 w
as shown to degrade plant RNA. The RNase activity of recombinant Bet v
1 was 180 units . mg(-1).