Identification of A chain cleavage sites in intact insulin produced by insulin protease and isolated hepatocytes

Duckworth, William C.; Hamel, Frederick G.; Liepnieks, Juris J.; Peavy, Daniel E.; Ryan, Michael P.; Hermodson, Mark A.; Frank, Bruce H.

doi:10.1016/0006-291x(87)90975-2

Cited by 25 publications

(8 citation statements)

References 12 publications

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“…Amino acid sequence comparisons have not revealed any significant similarity between different IDE substrates, suggesting that the enzyme recognizes some unidentified higher order structure. This idea is supported by the observation that the IDE cleavages are generally grouped on the same side of substrate molecules when viewing the three‐dimensional structure [20, 21]. In this report, it is proposed that IDE specificity is based on recognition of the structural elements that predetermine the ability of peptides to form amyloid fibrils.…”

Section: Introductionmentioning

confidence: 79%

Amyloidogenic determinant as a substrate recognition motif of insulin‐degrading enzyme

Kurochkin¹

1998

FEBS Letters

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Insulin-degrading enzyme (IDE) is an evolutionarily conserved neutral thiol metalloprotease expressed in all mammalian tissues whose biological role is not well established. IDE has highly selective substrate specificity. It degrades insulin, glucagon, atrial natriuretic peptide, transforming growth factor K K but does not act on related hormones and growth factors. The structural properties determining whether a peptide is an IDE substrate are essentially unknown. The reported cleavage sites are not consistent with simple peptide-bond recognition and it was proposed that IDE recognizes in its substrates some elements of tertiary structure. We noticed that although IDE substrates are functionally unrelated, the majority of them share a specific property, an ability to form under certain conditions amyloid fibrils. Utilizing the residue pattern recognition procedure, this study reveals a common motif in the sequences of IDE substrates, HNHHHPSH, where H is wholly or partly hydrophobic character, N is small and neutral, P is polar, and S is polar and/or small amino acid residue. It is proposed that this sequence motif predetermines a structure recognized by IDE. The identified motif appears to be essentially the same as the proposed earlier consensus sequence for amyloid-forming peptides [Turnell and Finch, J. Mol. Biol. 227 (1992) 1205^1223]. The study suggests that IDE may play a role in elimination of potentially toxic amyloidogenic peptides.z 1998 Federation of European Biochemical Societies.

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Section: Introductionmentioning

confidence: 79%

Amyloidogenic determinant as a substrate recognition motif of insulin‐degrading enzyme

Kurochkin¹

1998

FEBS Letters

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“…The major radioactive fraction from the incubation with human liver cytosol was subjected to NH 2 -terminal sequencing. Radioactivity was released during the 14th cycle of the sequence (data not shown), indicating a peptide composition of at least 125 I-A chain (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). The similarity with the metabolic profile formed by PDI with labeled and unlabeled HI in conjunction with the definitive sequence of the unlabeled peptide fragment is consistent with the formation of intact 125 I-(A14)-A chain by human liver cytosol.…”

Section: Resultsmentioning

confidence: 99%

“…Insulin protease, purified from rat skeletal muscle and liver (2,10), and IDE, purified from human erythrocytes (11), have very similar biochemical, catalytic, and antigenic properties and are apparently identical (12). This enzyme cleaves insulin at specific sites in the A-and B chains (13,14), although the sequence of cleavage events is unclear. Cleavage sites produced by the purified enzyme are very similar to those identified with intact cells or isolated organ systems (3,(13)(14)(15)(16) and are consistent with peptide intermediates isolated in vivo (17).…”

mentioning

confidence: 99%

“…This enzyme cleaves insulin at specific sites in the A-and B chains (13,14), although the sequence of cleavage events is unclear. Cleavage sites produced by the purified enzyme are very similar to those identified with intact cells or isolated organ systems (3,(13)(14)(15)(16) and are consistent with peptide intermediates isolated in vivo (17). These findings have supported the physiological significance of this enzyme in insulin degradation.…”

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confidence: 99%

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Mechanisms Involved in Degradation of Human Insulin by Cytosolic Fractions of Human, Monkey, and Rat Liver

Wroblewski

Masnyk²,

Khambatta³

et al. 1992

Diabetes

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The degradation of native and 125I-labeled human insulin (HI) was examined in the cytosolic fraction of human, monkey, and rat liver. The purpose of these studies was to provide a species comparison of the interaction of insulin-degrading enzyme (IDE) and protein disulfide isomerase (PDI) in the degradation of HI. Western-blot analysis with monoclonal antibodies indicated the presence of both IDE and PDI in the cytosolic fraction of human and monkey liver. In contrast, rat liver cytosol contained, detectable levels of IDE only. A species comparison of metabolic profiles was performed by fractionating peptide products with reversed-phase high-performance liquid chromatography. After a 60-min incubation, human liver cytosol degraded unlabeled HI into three major products. Two of these peptides coeluted with the products of the incubation of HI with purified rat liver PDI. The three peptides were isolated and determined by NH2-terminal sequence analysis to be intact A chain, B chain, and des(Phe1)-B chain. Human liver cytosol also formed 125I-A chain and 125I-B chain as major products when specifically labeled 125I-HI isomers were used as substrate. Significant proteolytic degradation was observed only when reactions with human liver cytosol were supplemented with Mn2+. In contrast, monkey and rat liver cytosol proteolytically degraded 125I-HI isomers to small peptide fragments. The rat and monkey metabolic profiles were similar to each other and to that observed with Mn(2+)-supplemented human liver cytosol. Proteolysis in monkey and rat was sensitive to inhibition by EDTA.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…3) Bacitracin, a potent inhibiter of insulinglucagon protease, inhibits intracellular degradation of insulin by rat liver (Juul and Jones, 1982). 4) Insulin degradation products (specific cleavage sites) produced by insulin-glucagon protease in a cell-free system are the same as those produced by isolated hepatocytes (Muir et al, 1986;Duckworth et al, 1987Duckworth et al, , 1988. Identical cleavage sites produced by hepatocytes and cell-free insulin-glucagon protease strongly suggest that this enzyme is a major mechanism for insulin degradation by hepatocytes.…”

Section: Insulinmentioning

confidence: 99%

Hepatocellular processing of endocytosed proteins

Burwen

Jones

1990

J. Elec. Microsc. Tech.

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In conclusion, proteins of hepatobiliary transport utilize receptor-mediated endocytosis and intracellular vesicles and rely on functionally dynamic microtubules for their transport by hepatocytes. The many diverse transport pathways in hepatocytes reflect the many functions served by the uptake of various proteins from the blood. The mechanisms of sorting of ligands and their receptors in endosomes and the factors that regulate the intracellular transport pathways are not yet known. Future investigations in this area promise to yield many exciting discoveries about the hepatocellular processing of proteins.

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Identification of A chain cleavage sites in intact insulin produced by insulin protease and isolated hepatocytes

Cited by 25 publications

References 12 publications

Amyloidogenic determinant as a substrate recognition motif of insulin‐degrading enzyme

Amyloidogenic determinant as a substrate recognition motif of insulin‐degrading enzyme

Mechanisms Involved in Degradation of Human Insulin by Cytosolic Fractions of Human, Monkey, and Rat Liver

Hepatocellular processing of endocytosed proteins

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