1b9e
From Proteopedia
HUMAN INSULIN MUTANT SERB9GLU
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] 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. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe structure of human insulin mutant B9 (Ser-->Glu) was determined by an X-ray crystallographic method at 2.5 A resolution with an R factor of 0.165 under non-crystallographic restraints. The crystals were grown at low pH (<3.8) and belong to the orthorhombic P2(1)2(1)2(1) space group with unit-cell dimensions a = 44.54, b = 46.40, c = 51.85 A and one dimer per asymmetric unit without further aggregation. The structure in this crystal form can be regarded as a model for a discrete insulin dimer and displays the following features compared with the structure of 2Zn insulin. (i) The overall dimer is expanded and more symmetric. The two A chains are about 2 A more distant from each other, while the two B chains are about 0.8 A further apart. Both monomers are more similar to molecule 1 than molecule 2 of the 2Zn insulin dimer. (ii) The dimer structure is stabilized by protonation and neutralization of the carboxyl groups at lower pH and, in addition, by formation of a hydrogen-bond network among the side chains of residues GluB9, HisB13 and HisB10 on the dimer-forming surface of both monomers, resulting from a structural rearrangement. (iii) The B-chain amino-terminal segment is in an open state (O state), i.e. a state different from the well known R and T states found in the insulin hexamer. In the O state, the B-chain N-terminal segment is in an extended conformation and is detached from the rest of the molecule. This conformational state has also been observed in the monomeric crystal structure of despentapeptide (B26-B30) and desheptapeptide (B24-B30) insulin, as well as in the solution structure of an engineered insulin monomer. It suggests that the O state may be the characteristic conformation of insulin in lower aggregation forms and may be relevant to the formation of insulin fibrils. In addition, based on the crystallization process, the smallest possible building blocks of insulin crystal are also discussed. Structure of an insulin dimer in an orthorhombic crystal: the structure analysis of a human insulin mutant (B9 Ser-->Glu).,Yao ZP, Zeng ZH, Li HM, Zhang Y, Feng YM, Wang DC Acta Crystallogr D Biol Crystallogr. 1999 Sep;55(Pt 9):1524-32. PMID:10489447[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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