Vitellin
protein found in egg yolk
In biochemistry, vitellin is a generic name for major of many phosphoproteins found in egg yolk.
Vitellin has been known since the 1900s. The periodic acid-Schiff method and Sudan black B dye was used to help determine that Vitellin is a glycolipoprotein because it stained positive when tested. This protein was found to weigh ~540 kDa, given the weight of each of its 4 major subunits.
Vitellin is essential in the fertilization process, and embryonic development in egg-laying organisms.
This phosphoprotein acts as a membrane, 1-3.5μm, that encloses the egg that comprises at least five glycoproteins that resemble the zona pellucida evident in mammalian organisms. When the egg is fertilized, it buds off from the gamete surface, which results in the fertilization of the membrane in most invertebrates, amphibians, birds, and fishes. During fertilization, the acrosome of the sperm interacts with the vitelline envelope that has species-specific recognition and binding for the sperm. The vitelline membrane consists of two major layers found below the ovary and the outer layer found in the oviduct. This membrane supports the yolk and separates from the albumen, or egg white.
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This entry incorporates text from “Vitellin” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.