A comment on the absence of calcium regulation of human thioredoxin reductase

Oblong, John E.; Powis, Garth

doi:10.1016/0014-5793(93)81667-o

Cited by 8 publications

(6 citation statements)

References 15 publications

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“…In addition, a previous study suggested that Ca 2ϩ might be a potential inhibitor of mammalian TR (25)(26)(27), although another study found no inhibitory effects of calcium on TR1 activity (28). The possibility remained that the differences observed were due to analyses of different TR isozymes.…”

Section: Identification and Subcellularmentioning

confidence: 77%

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Characterization of Alternative Cytosolic Forms and Cellular Targets of Mouse Mitochondrial Thioredoxin Reductase

Turanov

Gladyshev

2006

Journal of Biological Chemistry

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Thioredoxin reductase (TR) and thioredoxin (Trx) define a major cellular redox system that maintains cysteine residues in numerous proteins in the reduced state. Both cytosolic (TR1 and Trx1) and mitochondrial (TR3 and Trx2) enzymes are essential in mammals, but the function of the mitochondrial system is less understood. In this study, we characterized subcellular localization of three TR3 forms that are generated by alternative first exon splicing and that differ in their N-terminal sequences. Only one of these forms resides in mitochondria, whereas the two other isoforms are cytosolic. Consistent with this finding, TR3 did not have catalytic preferences for mitochondrial Trx2 versus cytosolic Trx1, both of which could serve as TR3 substrates. Similarly, TR1 was equally active with Trx1, Trx2, or a bacterial Trx. We generated recombinant selenoprotein forms of TR1 and TR3 and found that these enzymes were inhibited by zinc, but not by calcium or cobalt ions. We further developed a proteomic method for identification of targets of TRs in mammalian cells utilizing affinity columns containing recombinant TR3 forms differing in C-terminal sequences. Using this procedure, we found that Trx1 was the major target of TR3 in both rat and mouse liver cytosol. The truncated form of TR3 lacking selenocysteine was particularly efficient in binding Trx1, consistent with the previously observed role of truncated TR1 in apoptosis. Overall, these data establish that the function of TR3 is not limited to its role in Trx2 reduction.

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Section: Identification and Subcellularmentioning

confidence: 77%

“…However, which TR isozyme is the most abundant in skin cells and was inhibited in these studies is not known. Subsequently, TR1 was reported to be insensitive to calcium inhibition (28,35). However, the most recent study found that TR1, but not TR3, is inhibited by Ca 2ϩ (36).…”

Section: Discussionmentioning

confidence: 99%

Characterization of Alternative Cytosolic Forms and Cellular Targets of Mouse Mitochondrial Thioredoxin Reductase

Turanov

Gladyshev

2006

Journal of Biological Chemistry

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“…80 226.01 f 18.54 63. 82 6723 7414 6304 8009 2009 3102 9507 2311 4818 6226 4329 6323 8302 9126 5009 3313 7107 9123 5122 7806 3807 6716 9048 5209 7409 8402 4010 6111 81 13 8219 4211 3106 1118 8315 9202 3808 5012 3408 6709 3308 2120 9702 8120 41 17 302 8012 8135 3109 6308 9106 8107 8118 3817 6024 2003 8105 3301 7224 5703 21 17 6717 8412 3309 3103 2209 61 I1 27 1116 3310 3104 2503 2206 2007 3403 3410 6503 102 1002 5202 2204 2009 1506 4305 3507 3405 4309 3107 4502 2505 5205 1107 2108 1207 3005 507 4205 2304 6208…”

Section: Not Detectedunclassified

A qualitative and quantitative protein database approach identifies individual and groups of functionally related proteins that are differentially regulated in simian virus 40 (SV40) transformed human keratinocytes: An overview of the functional changes associated with the transformed phenotype

Celis

Olsen

1994

Electrophoresis

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A qualitative and quantitative two-dimensional (2-D) gel database approach has been used to identify individual and groups of proteins that are differentially regulated in simian virus 40 (SV40) transformed human keratinocytes (K14). Five hundred and sixty [35S]methionine-labeled proteins (462 isoelectric focusing, IEF; 98 nonequilibrium pH gradient electrophoresis, NEPHGE), out of the 3038 recorded in the master keratinocyte database, were excised from dry, silver-stained gels of normal proliferating primary keratinocytes and K14 cells and the radioactivity was determined by liquid scintillation counting. Two hundred and thirty five proteins were found to be either up- (177) or down-regulated (58) in the transformed cells by 50% or more, and of these, 115 corresponded to known proteins in the keratinocyte database (J.E. Celis et al., Electrophoresis 1993, 14, 1091-1198). The lowest abundance acidic protein quantitated was present in about 60,000 molecules per cell, assuming a value of 10(8) molecules per cell for total actin. The results identified individual, and groups of functionally related proteins that are differentially regulated in K14 keratinocytes and that play a role in a variety of cellular activities that include general metabolism, the cytoskeleton, DNA replication and cell proliferation, transcription and translation, protein folding, assembly, repair and turnover, membrane traffic, signal transduction, and differentiation. In addition, the results revealed several transformation sensitive proteins of unknown identity in the database as well as known proteins of yet undefined functions. Within the latter group, members of the S100 protein family--whose genes are clustered on human chromosome 1q21--were among the highest down-regulated proteins in K14 keratinocytes. Visual inspection of films exposed for different periods of time revealed only one new protein in the transformed K14 keratinocytes and this corresponded to keratin 18, a cytokeratin expressed mainly by simple epithelia. Besides providing with the first global overview of the functional changes associated with the transformed phenotype of human keratinocytes, the data strengthened previous evidence indicating that transformation results in the abnormal expression of normal genes rather than in the expression of new ones.

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“…The cytosolic isoform of TGR shows a noticeably higher sensitivity to calcium ion inhibition in comparison to the corresponding mitochondrial isoform [10]. Taking into account the strict similarity between calcium and lanthanum ions, we have studied the effects of LaCl 3 on TrxR, in order to make a comparison with the results previously obtained on TrxR treated with calcium ions, especially considering the differential and contrasting inhibitory effects observed with this cation [1][2][3][4][5][6][7][8]. Lanthanum has an ionic radius similar to that of calcium and exhibits comparable coordination chemistry [11,12].…”

Section: Introductionmentioning

confidence: 97%

“…Moreover, the effect of calcium on TrxR still is an open problem as some reports indicate that TrxR is inhibited by calcium ions [1][2][3][4][5], while other studies show no effect of calcium ions even at relatively high concentrations [6][7][8]. This ambiguity probably depends on the different enzyme preparations under study (e.g.…”

Section: Introductionmentioning

confidence: 99%