~ 1497 ~ Journal of Entomology and Zoology Studies 2018; 6(4): 1497-1503 E-ISSN: 2320-7078 P-ISSN: 2349-6800 JEZS 2018; 6(4): 1497-1503 © 2018 JEZS Received: 04-05-2018 Accepted: 05-06-2018 Kanaka KK Indian Veterinary Research Institute, Izatnagar, Utter Pradesh, India Jeevan C National Dairy Research Institute, Karnal, Haryana, India Chethan Raj R Indian Veterinary Research Institute, Izatnagar, Utter Pradesh, India NG Sagar Indian Veterinary Research Institute, Izatnagar, Utter Pradesh, India Rajendra Prasad Indian Veterinary Research Institute, Izatnagar, Utter Pradesh, India C Kotresh Prasad National Dairy Research Institute, Karnal, Haryana, India Shruthi S Indian Veterinary Research Institute, Izatnagar, Utter Pradesh, India Correspondence Kanaka KK Indian Veterinary Research Institute, Izatnagar, Utter Pradesh, India A review on ovalbumin gene in poultry Kanaka KK, Jeevan C, Chethan Raj R, NG Sagar, Rajendra Prasad, C Kotresh Prasad and Shruthi S Abstract Ovalbumin is a major protein in the egg white. It is a monomeric phosphor glycoprotein with a known complete amino acid sequence of 386 residues. Due to its structural similarities with the serine protease inhibitors (Ser PIns), it is included in the serpin super family, although it lacks inhibitory activities. The size of the entire ovalbumin gene in poultry is approximately 7.6 kb of DNA with 7 exons and 6 introns, in order to code for mRNA of 1859 nucleotides. Tubular gland cells of magnum are responsible for the production of ovalbumin protein. Ovalbumin gene in poultry have been found polymorphic in various populations in various parts of gene including coding sequence, promoter region etc., ovalbumin serve as a source of amino acid and may also have a more active/direct function on developing tissues and believed to play a crucial role in bio mineralization. Keywords: Ovalbumin, characterization, expression, polymorphism Introduction Ovalbumin, a SERPIN family protein is the major protein in the egg white. Egg white is composed of ~9.7-10.6% protein by weight [1] . Over 24 different proteins have been identified and isolated from egg white. Some of the major proteins include ovalbumin (54%), ovotransferrin (12%), ovomucoid (11%), ovomucin (3.5%), and lysozyme (3.4%) [1] . Ovalbumin has a molecular weight of 44.5kDa and is a monomeric phosphor glycoprotein with a known complete amino acid sequence of 386 residues. It is a storage protein and major source of amino acids for the developing embryo. Chicken ov-serpins are largely represented as 10 clade B serpins clustered on a 150 kb locus chromosome 2q [2, 3] . The size of the entire ovalbumin gene is approximately 7.6 kb of DNA in order to code for mRNA of 1859 nucleotides [4] . Intact ovalbumin is recovered in the extracts of many embryonic organs including the head, eye, heart, liver, intestine, spinal cord, muscle, dermis, and bone. This observation together with the absence of ovalbumin mRNA expression in these organs and with the fact that the neonate organs are no longer positive for ovalbumin shortly after hatching, suggests that egg white ovalbumin may not merely serve as a source of amino acid but may also have a more active/direct function on developing tissues [5] . In the vitelline membrane a total of 5 serpins have been identified with the predicted role in folliculogenesis, angiogenesis and in defence however role of ovalbumin is still unclear [6] . Ovalbumin in eggshell is believed to play a crucial role in calcium carbonate formation and amorphous calcium carbonate stabilization i.e. biomineralization, which is defined as the production of the hard tissue characterized by a specific minerals/organic matrix framework, by a living organism (7) . The objective of this study was to know the characteristics of ovalbumin gene, its expression profile and to know its polymorphism. 2. Ovalbumin The most abundant and central protein to egg white’s functional properties in foods is ovalbumin. Ovalbumin has a molecular weight of 44.5 kDa and is a monomeric phosphor glycoprotein with a known complete amino acid sequence of 386 residues [1] . It is a storage protein and major source of amino acids for the developing embryo. The N-terminus of ovalbumin is acetylated and contains four sulfhydryl groups and one disulfide bridge (Cys74- Cys121), which are inaccessible in the native state [8] . Although it is a secretion protein, ovalbumin is lacking an N-terminal leader sequence. Trans-membrane location is instead mediated by an internal sequence signal located within hydrophobic residues 21-47 [9] . Ovalbumin secondary structure has various motifs including α-helix (41%), β-sheet (34%),