関: protein isoform

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2012/09/22 08:06:30」(JST)

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A protein isoform is any of several different forms of the same protein. Different forms of a protein may be produced from related genes, or may arise from the same gene by alternative splicing. A large number of isoforms are caused by single-nucleotide polymorphisms or SNPs, small genetic differences between alleles of the same gene. These occur at specific individual nucleotide positions within a gene.

The discovery of isoforms partly explains the apparently small number of coding regions (genes) revealed by the human genome project: the ability to create categorically different proteins from the same gene increases the diversity of the proteome. Isoforms are readily described and discovered by microarray studies and cDNA libraries.

Glycoforms

A glycoform is an isoform of a protein that differs only with respect to the number or type of attached glycan. Glycoproteins often consist of a number of different glycoforms, with alterations in the attached saccharide or oligosaccharide. These modifications may result from differences in biosynthesis during the process of glycosylation, or due to the action of glycosidases or glycosyltransferases. Glycoforms may be detected through detailed chemical analysis of separated glycoforms, but more conveniently detected through differential reaction with lectins, as in lectin affinity chromatography and lectin affinity electrophoresis. Typical examples of glycoproteins consisting of glycoforms are the blood proteins as orosomucoid, antitrypsin, and haptoglobin. An unusual glycoform variation is seen in neuronal cell adhesion molecule, NCAM involving polysialic acids, PSA.

Examples

G-actin, despite its conserved nature, has varying number of isoforms, with a single isoform in yeasts and multiple (at least six in mammals) in eukaryotes.
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.
UDP-glucuronosyltransferase, an enzyme superfamily responsible for the detoxification pathway of many drugs, environmental pollutants, and toxic endogenous compounds has 16 known isoforms encoded in the human genome.^[1]

References

^ Barre L, Fournel-Gigleux S, Finel M, Netter P, Magdalou J, Ouzzine M (March 2007). "Substrate specificity of the human UDP-glucuronosyltransferase UGT2B4 and UGT2B7. Identification of a critical aromatic amino acid residue at position 33". FEBS J. 274 (5): 1256–64. doi:10.1111/j.1742-4658.2007.05670.x. PMID 17263731.

External links

Look up isoform in Wiktionary, the free dictionary.

MeSH entry protein isoforms
Definitions Isoform

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English Journal

A signature protein-based method to distinguish Mediterranean water buffalo and foreign breed milk.

Caira S, Pinto G, Balteanu VA, Chianese L, Addeo F.SourceUniversità degli Studi di Napoli "Federico II", Facoltà di Agraria Via Università, 100 80055 Portici, Napoli, Italy. caira@unina.it
Food chemistry.Food Chem.2013 Nov 1;141(1):597-603. doi: 10.1016/j.foodchem.2013.02.033. Epub 2013 Mar 15.
A novel genetic variant at the αs1-casein locus of water buffalo (WB), 8-residue shorter than its wild-type has been found and sequenced. The internal deletion of the peptide E(35)KVNELsT(42) was confirmed by the isolation of the junction peptide. The 8-residue deletion mutant has a molecular weigh
PMID 23768399

PHLP2 is essential and plays a role in ciliogenesis and microtubule assembly in Tetrahymena thermophila.

Bregier C, Krzemień-Ojak L, Włoga D, Jerka-Dziadosz M, Joachimiak E, Batko K, Filipiuk I, Smietanka U, Gaertig J, Fabczak S, Fabczak H.SourceDepartment of Cell Biology, Nencki Institute of Experimental Biology, Warsaw, Poland.
Journal of cellular physiology.J Cell Physiol.2013 Nov;228(11):2175-89. doi: 10.1002/jcp.24384.
Recent studies have implicated the phosducin-like protein-2 (PHLP2) in regulation of CCT, a chaperonin whose activity is essential for folding of tubulin and actin. However, the exact molecular function of PHLP2 is unclear. Here we investigate the significance of PHLP2 in a ciliated unicellular mode
PMID 23588994

AMP-activated protein kinase (AMPK) α2 subunit mediates glycolysis in postmortem skeletal muscle.

Liang J, Yang Q, Zhu MJ, Jin Y, Du M.SourceCollege of Food Science, Inner Mongolia Agricultural University, Hohhot, China; Department of Animal Sciences, Washington State University, Pullman, WA, United States.
Meat science.Meat Sci.2013 Nov;95(3):536-41. doi: 10.1016/j.meatsci.2013.05.025. Epub 2013 May 25.
Postmortem glycolysis is directly linked to the incidences of PSE (pale, soft and exudative) and DFD (dark, firm and dry) meats which cause significant loss to meat industry. AMP-activated protein kinase (AMPK) is a major regulator of postmortem glycolysis. However, there are two isoforms of the AMP
PMID 23793092

Japanese Journal

SLC25A13 Gene Analysis in Citrin Deficiency: Sixteen Novel Mutations in East Asian Patients, and the Mutation Distribution in a Large Pediatric Cohort in China

Song Yuan-Zong,Zhang Zhan-Hui,Lin Wei-Xia,Zhao Xin-Jing,Deng Mei,Ma Yan-Li,Guo Li,Chen Feng-Ping,Long Xiao-Ling,He Xiang-Ling,Sunada Yoshihide,Soneda Shun,Nakatomi Akiko,Dateki Sumito,Ngu Lock-Hock,Kobayashi Keiko,Saheki Takeyori
PLoS ONE 8(9), e74544, 2013-09-19
… Background:The human SLC25A13 gene encodes citrin, the liver-type mitochondrial aspartate/glutamate carrier isoform 2 (AGC2), and SLC25A13 mutations cause citrin deficiency (CD), a disease entity that encompasses different age-dependant clinical phenotypes such as Adult-onset Citrullinemia Type II (CTLN2) and Neonatal Intrahepatic Cholestasis caused by Citrin Deficiency (NICCD). …
NAID 120005343849

Simple extraction methods that prevent the artifactual conversion of chlorophyll to chlorophyllide during pigment isolation from leaf samples

Hu Xueyun,Tanaka Ayumi,Tanaka Ryouichi
Plant Methods 9, 2013-06-19
… Results: We evaluated the artifactual chlorophyllide production during chlorophyll extraction by comparing different extraction methods with wild-type and mutant Arabidopsis leaves that lack the major isoform of chlorophyllase. …
NAID 120005316990

クラスIIα 型phosphatidylinositel 3キナーゼは, 血管内皮細胞において小胞輸送の制御を介して血管新生及び血管バリア機能に必要である

吉田耕太郎
金沢大学十全医学会雑誌 122(2), 31-34, 2013-06-00
… The class II a-isoform of phosphatidylinositol 3-kinase (PI3K-C2α) is localized in endosomes, the trans-Golgi network and clathrin-coated vesicles; …
NAID 120005324081