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== Function == | == Function == | ||
[[http://www.uniprot.org/uniprot/INS_HUMAN INS_HUMAN]] Insulin decreases blood glucose concentration. It increases cell permeability to monosaccharides, amino acids and fatty acids. It accelerates glycolysis, the pentose phosphate cycle, and glycogen synthesis in liver. [[http://www.uniprot.org/uniprot/B2MG_HUMAN B2MG_HUMAN]] Component of the class I major histocompatibility complex (MHC). Involved in the presentation of peptide antigens to the immune system. | [[http://www.uniprot.org/uniprot/INS_HUMAN INS_HUMAN]] Insulin decreases blood glucose concentration. It increases cell permeability to monosaccharides, amino acids and fatty acids. It accelerates glycolysis, the pentose phosphate cycle, and glycogen synthesis in liver. [[http://www.uniprot.org/uniprot/B2MG_HUMAN B2MG_HUMAN]] Component of the class I major histocompatibility complex (MHC). Involved in the presentation of peptide antigens to the immune system. | ||
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== Publication Abstract from PubMed == | |||
The NOD mouse model of type 1 diabetes (T1D) continues to be an important tool for delineating the role of T-cell-mediated destruction of pancreatic beta-cells. However, little is known about the molecular mechanisms that enable this disease pathway. We show that insulin reactivity by a CD8+ T-cell clone known to induce T1D is characterised by weak T cell antigen receptor (TCR) binding to a relatively unstable peptide-major histocompatibility complex (pMHC). The structure of the native 9-mer and 10-mer insulin epitopes demonstrated that peptide residues 7 and 8 form a prominent solvent exposed bulge that could potentially be the main focus of TCR binding. The C-terminus of the peptide governed pMHC stability. Unexpectedly, we further demonstrate a novel mode of flexible peptide presentation in which the MHC peptide-binding groove is able to 'open the back door' to accommodate extra C-terminal peptide residues. | |||
Distortion of the MHC class I binding groove to accommodate an insulin-derived 10-mer peptide.,Motozono C, Pearson JA, De Leenheer E, Rizkallah PJ, Beck K, Trimby A, Sewell AK, Wong FS, Cole DK J Biol Chem. 2015 Jun 17. pii: jbc.M114.622522. PMID:26085090<ref>PMID:26085090</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
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== References == | == References == | ||
<references/> | <references/> |
Revision as of 15:07, 1 July 2015
Weak TCR binding to an unstable insulin epitope drives type 1 diabetesWeak TCR binding to an unstable insulin epitope drives type 1 diabetes
Structural highlights
Disease[INS_HUMAN] Defects in INS are the cause of familial hyperproinsulinemia (FHPRI) [MIM:176730].[1] [2] [3] [4] Defects in INS are a cause of diabetes mellitus insulin-dependent type 2 (IDDM2) [MIM:125852]. IDDM2 is a multifactorial disorder of glucose homeostasis that is characterized by susceptibility to ketoacidosis in the absence of insulin therapy. Clinical fetaures are polydipsia, polyphagia and polyuria which result from hyperglycemia-induced osmotic diuresis and secondary thirst. These derangements result in long-term complications that affect the eyes, kidneys, nerves, and blood vessels.[5] Defects in INS are a cause of diabetes mellitus permanent neonatal (PNDM) [MIM:606176]. PNDM is a rare form of diabetes distinct from childhood-onset autoimmune diabetes mellitus type 1. It is characterized by insulin-requiring hyperglycemia that is diagnosed within the first months of life. Permanent neonatal diabetes requires lifelong therapy.[6] [7] Defects in INS are a cause of maturity-onset diabetes of the young type 10 (MODY10) [MIM:613370]. MODY10 is a form of diabetes that is characterized by an autosomal dominant mode of inheritance, onset in childhood or early adulthood (usually before 25 years of age), a primary defect in insulin secretion and frequent insulin-independence at the beginning of the disease.[8] [9] [10] [B2MG_HUMAN] Defects in B2M are the cause of hypercatabolic hypoproteinemia (HYCATHYP) [MIM:241600]. Affected individuals show marked reduction in serum concentrations of immunoglobulin and albumin, probably due to rapid degradation.[11] Note=Beta-2-microglobulin may adopt the fibrillar configuration of amyloid in certain pathologic states. The capacity to assemble into amyloid fibrils is concentration dependent. Persistently high beta(2)-microglobulin serum levels lead to amyloidosis in patients on long-term hemodialysis.[12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] Function[INS_HUMAN] Insulin decreases blood glucose concentration. It increases cell permeability to monosaccharides, amino acids and fatty acids. It accelerates glycolysis, the pentose phosphate cycle, and glycogen synthesis in liver. [B2MG_HUMAN] Component of the class I major histocompatibility complex (MHC). Involved in the presentation of peptide antigens to the immune system. Publication Abstract from PubMedThe NOD mouse model of type 1 diabetes (T1D) continues to be an important tool for delineating the role of T-cell-mediated destruction of pancreatic beta-cells. However, little is known about the molecular mechanisms that enable this disease pathway. We show that insulin reactivity by a CD8+ T-cell clone known to induce T1D is characterised by weak T cell antigen receptor (TCR) binding to a relatively unstable peptide-major histocompatibility complex (pMHC). The structure of the native 9-mer and 10-mer insulin epitopes demonstrated that peptide residues 7 and 8 form a prominent solvent exposed bulge that could potentially be the main focus of TCR binding. The C-terminus of the peptide governed pMHC stability. Unexpectedly, we further demonstrate a novel mode of flexible peptide presentation in which the MHC peptide-binding groove is able to 'open the back door' to accommodate extra C-terminal peptide residues. Distortion of the MHC class I binding groove to accommodate an insulin-derived 10-mer peptide.,Motozono C, Pearson JA, De Leenheer E, Rizkallah PJ, Beck K, Trimby A, Sewell AK, Wong FS, Cole DK J Biol Chem. 2015 Jun 17. pii: jbc.M114.622522. PMID:26085090[25] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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