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A single mRNA, transcribed from an alternative, erythroid-specific, promoter, codes for two non-myristylated forms of NADH-cytochrome b5 reductase

Two forms of NADH-cytochrome b5 reductase are produced from one gene: a myristylated membrane-bound enzyme, expressed in all tissues, and a soluble, erythrocyte-specific, isoform. The two forms are identical in a large cytoplasmic domain (Mr approximately 30,000) and differ at the NH2-terminus, whic...

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Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1992
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Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2289487/
https://www.ncbi.nlm.nih.gov/pubmed/1577871
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description Two forms of NADH-cytochrome b5 reductase are produced from one gene: a myristylated membrane-bound enzyme, expressed in all tissues, and a soluble, erythrocyte-specific, isoform. The two forms are identical in a large cytoplasmic domain (Mr approximately 30,000) and differ at the NH2-terminus, which, in the membrane form, is responsible for binding to the bilayer, and which contains the myristylation consensus sequence and an additional 14 uncharged amino acids. To investigate how the two differently targeted forms of the reductase are produced, we cloned a reductase transcript from reticulocytes, and studied its relationship to the previously cloned liver cDNA. The reticulocyte transcript differs from the liver transcript in the 5' non-coding portion and at the beginning of the coding portion, where the seven codons specifying the myristoylation consensus are replaced by a reticulocyte-specific sequence which codes for 13 non-charged amino acids. Analysis of genomic reductase clones indicated that the ubiquitous transcript is generated from an upstream "housekeeping" type promoter, while the reticulocyte transcript originates from a downstream, erythroid- specific, promoter. In vitro translation of the reticulocyte-specific mRNA generated two products: a minor one originating from the first AUG, and a major one starting from a downstream AUG, as indicated by mutational analysis. Both the AUGs used as initiation codons were in an unfavorable sequence context. The major, lower relative molecular mass product behaved as a soluble protein, while the NH2-terminally extended minor product interacted with microsomes in vitro. The generation of soluble reductase from a downstream AUG was confirmed in vivo, in Xenopus oocytes. Thus, differently localized products, with respect both to tissues and to subcellular compartments, are generated from the same gene by a combination of transcriptional and translational mechanisms.
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spelling pubmed-22894872008-05-01 A single mRNA, transcribed from an alternative, erythroid-specific, promoter, codes for two non-myristylated forms of NADH-cytochrome b5 reductase J Cell Biol Articles Two forms of NADH-cytochrome b5 reductase are produced from one gene: a myristylated membrane-bound enzyme, expressed in all tissues, and a soluble, erythrocyte-specific, isoform. The two forms are identical in a large cytoplasmic domain (Mr approximately 30,000) and differ at the NH2-terminus, which, in the membrane form, is responsible for binding to the bilayer, and which contains the myristylation consensus sequence and an additional 14 uncharged amino acids. To investigate how the two differently targeted forms of the reductase are produced, we cloned a reductase transcript from reticulocytes, and studied its relationship to the previously cloned liver cDNA. The reticulocyte transcript differs from the liver transcript in the 5' non-coding portion and at the beginning of the coding portion, where the seven codons specifying the myristoylation consensus are replaced by a reticulocyte-specific sequence which codes for 13 non-charged amino acids. Analysis of genomic reductase clones indicated that the ubiquitous transcript is generated from an upstream "housekeeping" type promoter, while the reticulocyte transcript originates from a downstream, erythroid- specific, promoter. In vitro translation of the reticulocyte-specific mRNA generated two products: a minor one originating from the first AUG, and a major one starting from a downstream AUG, as indicated by mutational analysis. Both the AUGs used as initiation codons were in an unfavorable sequence context. The major, lower relative molecular mass product behaved as a soluble protein, while the NH2-terminally extended minor product interacted with microsomes in vitro. The generation of soluble reductase from a downstream AUG was confirmed in vivo, in Xenopus oocytes. Thus, differently localized products, with respect both to tissues and to subcellular compartments, are generated from the same gene by a combination of transcriptional and translational mechanisms. The Rockefeller University Press 1992-06-01 /pmc/articles/PMC2289487/ /pubmed/1577871 Text en This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
spellingShingle Articles
A single mRNA, transcribed from an alternative, erythroid-specific, promoter, codes for two non-myristylated forms of NADH-cytochrome b5 reductase
title A single mRNA, transcribed from an alternative, erythroid-specific, promoter, codes for two non-myristylated forms of NADH-cytochrome b5 reductase
title_full A single mRNA, transcribed from an alternative, erythroid-specific, promoter, codes for two non-myristylated forms of NADH-cytochrome b5 reductase
title_fullStr A single mRNA, transcribed from an alternative, erythroid-specific, promoter, codes for two non-myristylated forms of NADH-cytochrome b5 reductase
title_full_unstemmed A single mRNA, transcribed from an alternative, erythroid-specific, promoter, codes for two non-myristylated forms of NADH-cytochrome b5 reductase
title_short A single mRNA, transcribed from an alternative, erythroid-specific, promoter, codes for two non-myristylated forms of NADH-cytochrome b5 reductase
title_sort single mrna, transcribed from an alternative, erythroid-specific, promoter, codes for two non-myristylated forms of nadh-cytochrome b5 reductase
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2289487/
https://www.ncbi.nlm.nih.gov/pubmed/1577871