- Protein isoform
A protein isoform is a version of a
protein with only small differences to another isoform of the same protein. [http://en.wiktionary.org/wiki/isoform] Different forms of a protein may be produced from different but relatedgenes , or may arise from the same gene byalternative splicing . A large number of isoforms are caused bysingle nucleotide polymorphisms , small genetic differences betweenalleles of the same gene.The discovery of isoforms explains the apparently small number of coding
genes revealed in thehuman genome project : the ability to create categorically different proteins from the same gene increases the diversity of theproteome . Isoforms are readily described and discovered bymicroarray studies andcDNA libraries.Glycoforms
A glycoform is an isoform where different forms of a
glycoprotein have differentpolysaccharide s attached to them, by eitherposttranslational orcotranslational modifications.Examples
*
Creatine kinase , the presence of which in the blood can be used as an aid in the diagnosis of myocardial infarction, exists in 3 isoforms.
*Hyaluronan synthase , the enzyme responsible for the production of hyaluronan, has three isoforms in mammalian cells.Links
* [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=mesh&list_uids=68020033&dopt=Full MeSH entry protein isoforms]
* [http://ghr.nlm.nih.gov/glossary=isoforms Definitions Isoform]
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