The biological function of avidin is not known. Forms a strong non-covalent specific complex with biotin (one molecule of biotin per subunit of avidin). Homotetramer. Synthesized in hen oviduct and concentrated in egg white (where it represent 0.05% of the total protein). N-linked glycan at Asn-41 consists of GlcNAc(beta1-2)Man(alpha1-3)[GlcNAc(beta1-4)][Man(alpha1-?)Man(alpha1-6)] Man(beta1-4)GlcNAc(beta1-4)GlcNAc. Belongs to the avidin/streptavidin family.