APPLE ALLERGY - THE CDNA SEQUENCE OF THE MAJOR ALLERGEN OF APPLE, DETERMINED BY PERFORMING PCR WITH A PRIMER BASED ON THE N-TERMINAL AMINO-ACID-SEQUENCE, IS HIGHLY HOMOLOGOUS TO THE SEQUENCE OF THE MAJOR BIRCHPOLLEN ALLERGEN

Considering the known N-terminal amino acid sequence of the major appl e allergen, a polymerase chain reaction (PCR) primer was selected to a mplify cDNA encoding this protein. A single PCR product was obtained, cloned into Escherichia coli and subsequently sequenced. The missing 5 '-end of the apple cDNA sequence was obtained by a 5'-RACE method. The cDNA sequence showed 72% identity with the coding region of one of th e known isoforms of Bet v 1, the major allergen of birch pollen. The d educed amino acid sequence resulted in a 158-residue protein with a ca lculated molecular mass of 17.5 kDa and 63% amino acid sequence identi ty to Bet v 1. In addition, further protein alignments showed a high d egree of identity with allergens from other tree pollens and some 'pat hogenesis-related proteins' from food plants. According to internation al regulations the allergen was termed Mal d 1 for this protein, it be ing the first major allergen discovered and characterised in fruits of apple (Malus domestica).