摘要:

This work summarizes binding data that were obtained with partially purified glucocorticoid and progesterone receptors, as well as with a crude nuclear protein extract, to DNA sequences in and around hormonally regulated genes. The sequence recognition by the glucocorticoid receptor at the different defined glucocorticoid regulatory elements (GRE) is discussed and a consensus sequence formulated. A three dimensional representation gives an impression of the mode of interaction between the protein and the double helix of DNA. In the promoters of mouse mammary tomour virus (MTV) and chicken lysozyme overlapping binding sites for both, glucocorticoid and progestine-receptors are found that are responsible for the hormonal inducibility of the genes. In crude extract from rat liver nuclei, a nonhistone protein is found that specifically binds to sequences on the MTV-LTR region overlapping the GRE. The possible irrplication of this protein in hormonal regulation of transcription is discussed.

ISSN:0743-5800    

DOI:10.3109/07435808909036347

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

Heterogeneous nuclear RNAs (hnRNAs), some of which are mRNA precursors, and the mature mRNAs are associated in eukaryotic cells with specific proteins to form ribonucleoprotein complexes (RNP). The RNP proteins are likely to play a major role in the formation, packaging, processing, and function of mRNA. The major proteins that interact with hnRNA and with mRNA were identified by photochemical RNA-protein cross-linking in intact cells and monoclonal antibodies to several of these proteins were produced. Using these antibodies the hnRNP proteins were characterized and the hnRNP complex was isolated from vertebrate cell nuclei. The hnRNP complex is a unitary structure of consistent, defined and conserved components. The proteins of the hnRNP complex were identified and the general organization of hnRNA and proteins in the hRNP complex were studied.

ISSN:0743-5800    

DOI:10.3109/07435808909036348

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

ISSN:0743-5800    

DOI:10.3109/07435808909036349

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

ISSN:0743-5800    

DOI:10.3109/07435808909036350

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

A nearly full length ME cDNA has been obtained and sequenced. The identity has been established by comparison of the translated nucleotide sequence with the amino acid sequence of 7 tryptic peptides from purified ME.Northern analysis with this cDNA shows that ME mRNA consists of two different messages of about 27S and 21S.The size difference between two ME mRNAs (=27S and 21S) is attributed to the differences in the 3′noncoding regions.The relative ratios of the two ME mRNAs differ in various tissues examined (liver, heart, kidney, brain, lung, spleen, and testis). Their regulation by T3is tissue specific with coordinate stimulation of both mRNAs in liver, heart and kidney, suggesting a single promoter for both mRNAs and no stimulation of either in the other tissues.T3regulates ME mRNA synthesis via a dual-tissue specific mechanism by increasing the rate of transcription in liver and heart and stabilizing nuclear ME RNA sequences only in liver.

ISSN:0743-5800    

DOI:10.3109/07435808909036351

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

The level of myosin heavy chain (MHC) alpha mRNA and of MHC-beta mRNA was quantitated in the rat heart using a specific cDNA probe. In hypothyroid and diabetic hearts MHC-beta mRNA predominates, whereas in normal hearts MHC-alpha mRNA represents 80% of all MHC mRNA. Administration of 0.2 mg T3/100 g body wt. to hypothyroid rats led to an increase in MHC-alpha mRNA beginning at 3 h after injection and continued to rise until at 24 h control level of MHC-alpha mRNA were reached. In contrast, after administration of 2 units regular insulin to diabetic rats, MHC-alpha mRNA levels showed a small but significant increase already 30 min after insulin administration reaching a peak at 3 h and returning to diabetic values 5 h after insulin. The T3 response of other cardiac mRNAs was quantitated usingin vitrotranslation, separation of35S methionine labeled translational products and their quantitation by digital matrix photometry. An mRNA (spot 72b) coding for a translational product with a Mr 81,000 and pI of 5.4 showed a 3-fold increase in its level 1 h after T3administration. In view of the rapid response of spot 72b and the early response of MHC-alpha mRNA to insulin, it is currently unclear if the T3response of MHC-alpha mRNA represents a primary effect of T3.

ISSN:0743-5800    

DOI:10.3109/07435808909036352

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

ISSN:0743-5800    

DOI:10.3109/07435808909036353

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

ISSN:0743-5800    

DOI:10.3109/07435808909036354

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

In this presentation, I present evidence indicating a direct action of thyroid hormone at the level of the plasma membrane. Characteristically, the plasma membrane-mediated effects of thyroid hormones are prompt in onset, independent of new protein synthesis, and are associated with changes in the transmembrane transport of ions and substrates. The presence of specific binding sites for thyroid hormone in plasma membranes of various tissues and species, although inconclusive in itself, provides additional support for the direct action of thyroid hormone on the plasma membrane. A model for the mechanism o f action of thyroid hormone at the plasma membrane level to increase sugar uptake by rat thymocytes is delineated, and the physiological role of the plasma membrane-mediated action of thyroid hormone is discussed.

ISSN:0743-5800    

DOI:10.3109/07435808909036355

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

The Ca2+-ATPase of plasma membranes from a variety of tissues is subject to stimulationin vitro, and apparentlyin vivo, by physiological concentrations of iodothyronines regarded as biologically active in other bioassay systems. This calmodulin-dependent action of thyroid hormone is nongenomic, that is, directly on the cell membrane and independent of the cell nucleus. In the case of human erythrocyte Ca2+-ATPase, this assay of thyroid hormone bioactivity is attractive as anin vitro, readily-studied model of hormone action in a human cell. Enzyme activity is paralleled, as expected, by changes in calcium pump activity. Thyroid hormone action in this system is subject to modulation by glucose and by a variety of compounds which, like iodothyronines, are hydrophobic. The mechanism of thyroid hormone action on membrane Ca2+-ATPase involves, at least in part, membrane lipids, including components of the phosphatidylinositol cycle.The physiologic role of thyroid hormone action on cell membrane Ca2+-ATPase is speculative. In plasma membranes of nonexcitable and excitable tissues, ambient thyroid hormone may set basal activity of Ca2+-ATPase or magnitude of the enzymatic response to calmodulin Ca2+.

ISSN:0743-5800    

DOI:10.3109/07435808909036356

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor