Insulin glycosylated

Measure blood glucose levels at baseline and every 3 months to assess for glucose intolerance and insulin resistance. Periodic measurement of glycosylated hemoglobin (HbAlc) also may be useful.34... 

Kirkpatrick RB, Matico RE, McNulty DE, Strickler JE, Rosenberg M 1995 An abundantly secreted glycoprotein from Drosophila melanogaster is related to mammalian secretory proteins produced in rheumatoid tissues and by activated macrophages. Gene 153 147-154 Leconte I, Carpentier JL, Clauser E 1994 The functions of the human insulin receptor are affected in different ways by mutation of each of the four N-glycosylation sites in the fl subunit. J Biol Chem 269 18062-18071... 

Petruzzelli L, Herrera R, Arenas-Garcia R, Fernandez R, Bimbaum MJ, Rosen OM 1986 Isolation of a Drosophila genomic sequence homologous to the kinase domain of the human insulin receptor and detection of the phosphorylated Drosophila receptor with an anti-peptide antibody. Proc Natl Acad Sci USA 83 4710-4714 Podskalny J, McElduff A, Gorden P 1984 Insulin receptors on Chinese hamster ovary (CHO) cells altered insulin binding to glycosylation mutants. Biochem Biophys Res Commun 125 70-75... 

Raff I have a question about the insulin receptor glycosylation. Is it needed for function, or is it just needed to get the receptor to the plasma membrane in a stable form ... 

Bryant The work published on the mammalian insulin receptor shows that glycosylation is required for function. There is a mutagenesis study showing that there is a particular Asp residue, without which the receptor is expressed on the membrane but doesn t function (Leconte et al 1994). In other studies the biosynthesis of the oligosaccharides has been inhibited, and this has the same kind of effect (Podskalny et al 1984). 

Podskalny J, McElduff A, Gorden P 1984 Insulin receptors on Chinese hamster ovary (CHO) cells altered insulin binding to glycosylation mutants. Biochem Biophys Res Commun 125 70-75... 

Rouiller DG, Sharon N, McElduff A, Podskalny JM, Gorden P 1986 Lectins as probes of insulin receptor carbohydrate composition studies in glycosylation mutants of Chinese hamster ovarian cells with altered insulin binding. Endocrinology 118 1159-1165... 

Increase in glucose concentration —> displacement of glycosylated insulin by competitive binding —> release of glycosylated insulin... 

K. Ohtsubo, S. Takamatsu, M. T. Minowa, A. Yoshida, M. Takeuchi, and J. D. Marth, Dietary and genetic control of glucose transporter 2 glycosylation promotes insulin secretion in suppressing diabetes, Cell, 123 (2005) 1307-1321. 

Studies have shown that plants can make biologically active recombinant proteins through both transgenic and transient expression approaches. Although the plant post-translational machinery is similar to that of mammalian cells, there are some notable differences, e.g. differences in glycosylation, particularly the absence of sia-lation, which may impact the activity of certain proteins. The absence of mammalian enzymes may prevent complex maturation processes that are critical for the biological activity of proteins such as insulin. Fortunately these shortcomings affect the activity of only a limited number of proteins. 

At present, antioxidants are extensively studied as supplements for the treatment diabetic patients. Several clinical trials have been carried out with vitamin E. In 1991, Ceriello et al. [136] showed that supplementation of vitamin E to insulin-requiring diabetic patients reduced protein glycosylation without changing plasma glucose, probably due to the inhibition of the Maillard reaction. Then, Paolisso et al. [137] found that vitamin E decreased glucose level and improved insulin action in noninsulin-dependent diabetic patients. Recently, Jain et al. [138] showed that vitamin E supplementation increased glutathione level and diminished lipid peroxidation and HbAi level in erythrocytes of type 1 diabetic children. Similarly, Skyrme-Jones et al. [139] demonstrated that vitamin E supplementation improved endothelial vasodilator function in type 1 diabetic children supposedly due to the suppression of LDL oxidation. Devaraj et al. [140] used the urinary F2-isoprostane test for the estimate of LDL oxidation in type 2 diabetics. They also found that LDL oxidation decreased after vitamin E supplementation to patients. 

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