Characterization of a birch pollen allergen, Bet v III, representing a novel class of Ca2+ binding proteins: specific expression in mature pollen and dependence of patients' IgE binding on protein-bound Ca2+.
A cDNA coding for a birch pollen allergen, Bet v III, with significant sequence homology to Ca2+ binding proteins was isolated from an expression cDNA library using serum IgE from a patient who was allergic to pollen. The deduced amino acid sequence of the pollen allergen contained three typical Ca2+ binding sites. Peptides mimicking the Ca2+ binding sites of Bet v III were synthesized and shown to bind 45Ca in blot overlays. The binding of patients' IgE to the recombinant allergen depended on the native protein conformation and protein-bound Ca2+. Depletion of Ca2+ led to a reversible loss of the IgE binding thus representing a conformational IgE epitope adopted by a polypeptide upon Ca2+ binding. By RNA hybridization it was demonstrated that Bet v III is expressed preferentially in mature pollen. Bet v III therefore represents a pollen allergen which because of its unique structural features also belongs to a novel class of Ca2+ binding proteins.
Seiberler
S
S
Institute of General and Experimental Pathology, AKH, University of Vienna, Austria.
Scheiner
O
O
Kraft
D
D
Lonsdale
D
D
Valenta
R
R
D000485:Allergens / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D052179:Antigens, Plant; D001483:Base Sequence; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary; D000939:Epitopes / Q000737:chemistry; D006801:Humans; D007073:Immunoglobulin E / Q000378:metabolism*; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011058:Pollen / Q000235:genetics* / Q000378:metabolism; D011487:Protein Conformation; D012333:RNA, Messenger / Q000032:analysis; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic; D014197:Trees
D000485:Allergens; D052179:Antigens, Plant; D002135:Calcium-Binding Proteins; D018076:DNA, Complementary; D000939:Epitopes; D010455:Peptides; D010940:Plant Proteins; D012333:RNA, Messenger; C088954:BETVIII protein, Betula pendula; D007073:Immunoglobulin E; D002118:Calcium