Major apple allergen Mal d 1 (Mal d 1)

Major apple allergen Mal d 1 is a 17.5 kDa pathogenesis-related class 10 (PR-10) protein recognized as the predominant allergen responsible for apple (Malus domestica) allergies, particularly in Europe and Northern America[1][2][3]. It shares high sequence and structural similarity to the major birch pollen allergen Bet v 1, leading to frequent immunological cross-reactivity: individuals sensitized to birch pollen often experience allergic reactions upon consuming apples due to the structural similarity triggering IgE-mediated responses[1][2][3]. Mal d 1 is present in both the peel and pulp of apples (higher in the peel) and exists as multiple isoallergens encoded by a large gene family[3]. It is a cytosolic, heat- and protease-labile protein that adopts a canonical PR-10 fold, consisting of a large hydrophobic cavity formed by a seven-stranded β-sheet and three α-helices[1][2]. Biologically, Mal d 1 has a role in plant defense against biotic and abiotic stresses, but in human health, its main relevance is as the molecular trigger of apple-induced food allergies, including oral allergy syndrome and, less commonly, systemic allergic reactions[1][2][3].

Other names

Bet v 1-like proteinPR-10 proteinPathogenesis-related class 10 proteinGroup 1 apple allergenApple major allergenApple Bet v 1 homolog