SERPINB14
Domain
The uncleaved signal peptide becomes available for membrane translocation of ovalbumin when the nascent chain is 50 to 60 residues long. The hydrophobic sequence, which lies between residues 27 and 43, folds back on the preceding residues to form an amphipathic hairpin structure which is the signal element recognized by the membrane.
Unlike other serpins, after protease cleavage at the P-P' site, ovalbumin does not have the ability to undergo the conformational transition into the loop-inserted reactive-center-containing thermostabilized form. The bulky arginine residue (Arg-340) at the hinge region appears to be responsible for this lack of loop-inserted conformational change, but not for the absence of serpin inhibitory activity.
During storage of fertilized and non-fertilized eggs or under alkaline conditions, the native ovalbumin conformer (N-ovalbumin) is transformed into a thermostabilized conformer, S-ovalbumin. Ser-165, Ser-237 and Ser-321 take on a D-configuration in this conformer and may be responsible for the thermostability.
Function
Non-inhibitory serpin. Storage protein of egg white.
Post-translational modifications
Undergoes proteolytic cleavage first at the canonical P1-P1' site, and then at the P8-P7 site by subtilisin.
Sequence Similarities
Belongs to the serpin family. Ov-serpin subfamily.
Tissue Specificity
Major protein of egg white. Expressed in the magnum of the oviduct (at protein level) (PubMed:25436390).
Cellular localization
- Secreted
Alternative names
Ovalbumin, Allergen Gal d II, Egg albumin, Plakalbumin, SERPINB14, OVA