Bet v I allergen is a family of protein allergens. Allergies are hypersensitivity reactions of the immune system to specific ☀️ substances called allergens (such as pollen, stings, drugs, or food) that, in most people, result in no symptoms.
Trees within the ☀️ order Fagales possess particularly potent allergens, e.g. the prototypical Bet v 1, the major white birch (Betula verrucosa - now ☀️ called B. pendula) pollen antigen. Bet v 1 is the main cause of type I allergies observed in early spring. ☀️ Type I, or immunoglobulin E-mediated (IgE-mediated) allergies affect 1 in 5 people in Europe and North America. Commonly observed symptoms ☀️ are hay fever, dermatitis, asthma and, in severe cases, anaphylactic shock. First contact with these allergens results in sensitisation; subsequent ☀️ contact produces a cross-linking reaction of IgE on mast cells and concomitant release of histamine. The inevitable symptoms of an ☀️ allergic reaction ensue.
Categorization [ edit ]
A nomenclature system has been established for antigens (allergens) that cause IgE-mediated atopic allergies in ☀️ humans.[2] This nomenclature system is defined by a designation that is composed of the first three letters of the genus; ☀️ a space; the first letter of the species name; a space and an Arabic number. In the event that two ☀️ species names have identical designations, they are discriminated from one another by adding one or more letters (as necessary) to ☀️ each species designation.
The allergens in this family include allergens with the following designations: Bet v 1, Dau c 1, and ☀️ Pru a 1. Other proteins belonging to this family include the major pollen allergens:
Structure [ edit ]
NMR analysis[3] has confirmed ☀️ earlier predictions of the protein structure and site of the major T-cell epitope.[4] The Bet v 1 protein comprises 6 ☀️ anti-parallel beta-strands and 3 alpha-helices. Four of the strands dominate the global fold, and 2 of the helices form a ☀️ C-terminal amphipathic helical motif. This motif is believed to be the T-cell epitope. However, one very striking feature of the ☀️ three-dimensional structure of Bet v 1 is the presence of a large hydrophobic cavity, which is open to the exterior ☀️ and probably functions as a ligand binding site.[5]
The motif is also found in:
Additionally, the core domain of Bet v 1 ☀️ founds or is part of a superfamily of domains called SRPBCC (START/RHOalphaC/PITP/Bet v1/CoxG/CalC) that include the StAR-related lipid-transfer (START) domain.
Function ☀️ [ edit ]
The biological function of Bet v 1 is still under investigations. Bet v 1 harbors a large hydrophobic ☀️ pocket and is able to bind a large spectra of ligands in it like hormones[6] and siderophores like flavonols. It ☀️ belongs to the pathogenesis-related (PR) proteins, which are usually expressed upon infections and stressful conditions,[7] implicating a role in host ☀️ defense. In vitro, Bet v 1 has been shown to be immune-suppressive, due to its ability to bind to iron-flavonoid ☀️ complexes, which it can shuttle into human monocytic cells to increase their labile iron pool and stimulate the anti-inflammatory Arylhydrocarbon ☀️ receptor pathway (https://mdpi/2076-3921/12/1/42). As such, only without any ligand, Bet v 1 was able to mount a Th2-response and turned ☀️ into an allergen.[8]
References [ edit ]
