Messenger ribonucleic acid, mRNA

When the cell requires instructions for protein production, part of the code on DNA, starting at an initiator and ending at a stop codon, is converted into a more mobile form by transferring the DNA code into a matching RNA code on a messenger ribonucleic acid (mRNA), a process known as transcription. The decoding, or translation, of mRNA then takes place by special transfer ribonucleic acids (tRNA), which recognize individual codons as amino acids. The sequence of amino acids is assembled into a protein (see Proteins section). In summary, the codes on DNA... 

KhGH A natural, stmctural variant of hGH called 20-K hGH has been reported to occur in the pituitary as well as in the bloodstream (12,13). This variant, which lacks the 15 amino acid residues from Glu-32 to Gln-46, arises from an alternative splicing of the messenger ribonucleic acid (mRNA) (14). This variant shares many but not all of the biological properties of hGH. 

Cellular protein biosynthesis involves the following steps. One strand of double-stranded DNA serves as a template strand for the synthesis of a complementary single-stranded messenger ribonucleic acid (mRNA) in a process called transcription. This mRNA in turn serves as a template to direct the synthesis of the protein in a process called translation. The codons of the mRNA are read sequentially by transfer RNA (tRNA) molecules, which bind specifically to the mRNA via triplets of nucleotides that are complementary to the particular codon, called an anticodon. Protein synthesis occurs on a ribosome, a complex consisting of more than 50 different proteins and several stmctural RNA molecules, which moves along the mRNA and mediates the binding of the tRNA molecules and the formation of the nascent peptide chain. The tRNA molecule carries an activated form of the specific amino acid to the ribosome where it is added to the end of the growing peptide chain. There is at least one tRNA for each amino acid. 

Meso-tetraaryl porphyrins, 14 552 Mesothelioma, 3 316 Messenger ribonucleic acid (mRNA), expression profiling and, 13 354 Messenger RNAs (mRNA), 12 449, 454, 473, 515 17 614, 627 20 824. See also mRNA synthesis... 

Ribosomal synthesis of peptides proceeds through translation of messenger ribonucleic acid (mRNA) and utilizes the 20 primary L-a-amino acids. These amino acids are incorporated with the use of specific transfer ribonucleic acid (tRNA) codons. The 20 primary a-amino acids, with the exception of glycine that is achiral, are characterized by an L-configuration at the a-position (Figure 1). In general, most proteins are found to be composed of these 20 L-a-amino acids, as such they are referred to as protein amino acids. 

Messenger ribonucleic acid (mRNA)—Messenger RNA copy of a gene used to make a protein in a cell it is complementary to and will bind to the DNA gene. 

All corticosteroids have the same general mechanism of action they traverse cell membranes and bind to a specific cytoplasmic receptor. The steroid-receptor complex translocates to the cell nucleus, where it attaches to nuclear binding sites and initiates synthesis of messenger ribonucleic acid (mRNA). The novel proteins that are formed may exert a variety of effects on cellular functions. The precise mechanisms whereby the corticosteroids exert their therapeutic benefit in asthma remain unclear, although the benefit is likely to be due to several actions rather than one specific action and is related to their ability to inhibit inflammatory processes. At the molecular level, corticosteroids regulate the transcription of a number of genes, including those for several cytokines. 

A change in expression of APP messenger ribonucleic acid (mRNA) has been shown to be affected by a number of potential pharmacologically active... 

The investigators measured messenger ribonucleic acid (mRNA) expression levels of MDRl and CYP3A4 in mucosal cells of the upper jejunum collected during living-donor liver transplantation in 48 recipients. Tacrolimus was initiated at an oral dose of 0.075 mg/kg every 12 hours and adjusted on the basis of trough levels in whole blood. 

The expression of the immediate early gene (IEG) c-fos has been extensively used as a functional marker of brain activity in neuroscience including sleep research (53-55). In most cell types, the basal level of c-fos expression is relatively low however, c-fos messenger ribonucleic acid (mRNA) and Fos protein can be rapidly and transiently induced by a diverse range of extracellular stimuli. Several laboratories have found that both c-Fos protein and mRNA levels decrease in the cerebral cortex during sleep relative to wakefulness (56-59). This decline has been linked to a reduction in the firing rate of the locus ceruleus during sleep and the consequent reduction of norepinephrine release in the cortex (60). 

Relatively recently Fe/S proteins have been found to function in the regulation of biosynthesis. This can be by promoting deoxyribonucleic acid (DNA) transcription, e.g. the [2Fe-2S] containing Escherichia coli superoxide-activated (SoxR) transcription activator [10-12], or the presumably [4Fe-4S]-containing E. coli transcription factor fumarate nitrate reduction (FNR) [13,14], Alternatively, the Fe/S protein can act by interference with messenger ribonucleic acid (mRNA) translation, i.e., the iron regulatory proteins (IRPs) [15,16], These interactions are stoichiometric, therefore not catalytic. Presumably, they are also a form of sensoring, namely, of oxidants and/or iron [17],... 

Chemical Synthesis and Biological Properties of the S -Terminus of Eukaryotic Messenger Ribonucleic Acids (mRNA)... 

Alexander MJ (1999) Colocalization of neurotensin messenger ribonucleic acid (mRNA) and progesterone receptor mRNA in rat arcuate nucleus under estrogen-stimulated conditions. Endocrinology 740 4995-5003. 

T2. Tennant, M. K., Thrasher, J. B., Twomey, P. A., Drivdahl, R. H. Bimbaum, R. S., and Plymate, S. R., Protein and messenger ribonucleic acid (mRNA) for the type 1 insulin-like growth factor (IGF) receptor is decreased and IGF-II mRNA is increased in human prostate carcinoma compared to benign prostate epithelium. J. Clin. Endocrinol. Metab. 81, 3774—3782 (1996). 

For reduplication, the chains are separated and on each a new, complementary strand is synthesized by enzymes called DNA polymerases [652J. For protein biosynthesis, the DNA is copied (transcribed) into the messenger ribonucleic acid (mRNA) by the enzyme RNA polymerase (Fig. 20.2) where, in contrast to DNA, the deoxyribose is replaced by ribose and thymine by the equivalent uracil. Here again, the Watson-Crick base pair plays the crucial role so that the mRNA sequence is complementary to the DNA sequence. 

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