title: The Family Secrets of Avian Egg-Specific Ovalbumin and Its Related Proteins Y and X.
abstract: The ovalbumin gene family in Gallus gallus is composed of three homologous genes located within a 46 kb locus on chromosome 2: ovalbumin, ovalbumin-related protein Y (OVAY), and ovalbumin-related protein X (OVAX) genes. The expression of these genes in hen oviduct is under estrogen control, but their relative hormonal responsiveness and subsequent protein concentration in egg, is distinctive. Interestingly, all three proteins lack the classical signal peptide for secretion. Ovalbumin, OVAX, and OVAY belong to the serine protease inhibitor (serpin) family whose members share a common tertiary structure. Ovalbumin and OVAX are one of the few members of this family that do not express any protease inhibition activity whereas OVAY has been predicted to be inhibitory, by comparison with the consensus sequence for inhibitory serpins. In contrast to ovalbumin and OVAY, OVAX interacts with heparin, a negatively charged glycosaminoglycan, via a positively charged domain exposed at the surface of the molecule. Ovalbumin is the major egg white protein and might be a source of amino acids for the developing embryo. The physiological function of OVAY is not known, but recent data have revealed a possible role of this protein in early embryonic development. Considering the antibacterial activities of OVAX, this protein might play a role in egg defense. This review sheds light on the expression, biochemistry, and structural specificities of these three highly similar paralogs. It gives new clues in favor of diverging functions, which are likely to have arisen by duplication events from a common ancestral gene.
authors.affiliation: INRA, UR83 Recherches Avicoles, Fonction et Régulation des Protéines de l'Œuf, Nouzilly, France.
authors.forename: Mylene
authors.initials: M
authors.lastname: Da Silva
authors.affiliation: INRA, UR83 Recherches Avicoles, Métabolisme des Oiseaux, Croissance et Adaptation, Nouzilly, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Beauclercq
authors.affiliation: INRA, Plateforme d'Analyse Intégrative des Biomolécules, Laboratoire de Spectrométrie de Masse, Physiologie de la Reproduction et des Comportements, CNRS, UMR7247, Université François Rabelais de Tours, IFCE, Nouzilly, France.
authors.forename: Grégoire
authors.initials: G
authors.lastname: Harichaux
authors.affiliation: INRA, Plateforme d'Analyse Intégrative des Biomolécules, Laboratoire de Spectrométrie de Masse, Physiologie de la Reproduction et des Comportements, CNRS, UMR7247, Université François Rabelais de Tours, IFCE, Nouzilly, France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Labas
authors.affiliation: INRA, UR83 Recherches Avicoles, Fonction et Régulation des Protéines de l'Œuf, Nouzilly, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Guyot
authors.affiliation: INRA, UR83 Recherches Avicoles, Fonction et Régulation des Protéines de l'Œuf, Nouzilly, France.
authors.forename: Joel
authors.initials: J
authors.lastname: Gautron
authors.affiliation: INRA, UR83 Recherches Avicoles, Fonction et Régulation des Protéines de l'Œuf, Nouzilly, France.
authors.forename: Yves
authors.initials: Y
authors.lastname: Nys
authors.affiliation: INRA, UR83 Recherches Avicoles, Fonction et Régulation des Protéines de l'Œuf, Nouzilly, France srehault@tours.inra.fr.
authors.forename: Sophie
authors.initials: S
authors.lastname: Rehault-Godbert
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030161:Avian Proteins / Q000235:genetics* / Q000502:physiology*; D005075:Biological Evolution; D001717:Birds / Q000502:physiology*; D002645:Chickens; D004527:Egg Proteins / Q000235:genetics* / Q000502:physiology*; D006801:Humans; D008969:Molecular Sequence Data; D010047:Ovalbumin / Q000235:genetics* / Q000502:physiology*; D015843:Serpins / Q000235:genetics* / Q000502:physiology*
chemical_list: D030161:Avian Proteins; D004527:Egg Proteins; D015843:Serpins; D010047:Ovalbumin
keywords: chicken; egg; evolution; expression; function; ovalbumin; structure