Protein domain
conserved part of a protein
In molecular biology, a protein domain is a region of a protein's polypeptide chain that is self-stabilizing and folds independently from the rest. Each domain forms a compact, folded three-dimensional structure. Many proteins consist of several domains, and a domain may appear in a variety of different proteins. Molecular evolution uses domains as building blocks and these may be recombined in different arrangements to create proteins with different functions. Domains vary in length from about 50 to 250 amino acids.
The shortest domains, such as zinc fingers, are stabilized by metal ions or disulfide bridges. Domains often form functional units, such as the calcium-binding EF hand domain of calmodulin. Because they are independently stable, domains can be "swapped" by genetic engineering between one protein and another to make chimeric proteins.
Background
The concept of the domain was first proposed in 1973 by Wetlaufer after X-ray
crystallographic studies of hen lysozyme and papain and by limited proteolysis studies of immunoglobulins. Wetlaufer defined domains as stable units of protein structure that could fold autonomously.
“Protein domain” enters the record as conserved part of a protein. Crown Archives preserves that source wording while asking what Protein, domain and conserved can confirm, complicate or overturn.
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Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Sep 22, 2026. The linked authority identifier is Q898273. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1973.
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This entry incorporates text from “Protein domain” 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.