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N J Brand

Publications and source records attributed to N J Brand.

9 recordsLinked to original sources
PubMed1992

Gene expression during cardiac development.

The vertebrate heart forms as two concentric epithelial cylinders of myocardium and endocardium separated by an extended basement membrane matrix commonly referred to as cardiac jelly. Subsequent maturation involves a complex series of events including asymmetric changes in cell shape and division which contribute to bending and the formation of the bulboventricular loop, the formation of specialised tissues including endocardial cushion tissue of the atrioventricular (AV) and outflow tract regions, the development of conductive tissue and myocyte maturation leading to the overall pattern of expression characteristic of mature heart muscle. These processes depend on a precise spatial and temporal control of gene expression both of genes encoding regulatory molecules and those encoding structural components of the heart. In this chapter we address three aspects of cardiac development, namely, the determination of cell fate during formation of endocardial cushion tissue in the embryonic heart, transitions in troponin gene expression during fetal myocyte maturation, and the use of cloning techniques based on the polymerase chain reaction for identifying transcription factors present in the heart.

Animals↗
PubMed1991

Determination of the 5' exon structure of the human cardiac alpha-myosin heavy chain gene.

We have deduced the exon structure of the 5' untranslated region of the human cardiac alpha-myosin heavy chain gene by cloning a cDNA for this region using the polymerase chain reaction. Comparison of the cDNA and genomic DNA sequences demonstrates that the 5' non-coding region of the alpha-myosin heavy chain gene is interrupted by two introns of 645 and 337 nucleotides. Secondly we have identified the transcriptional start-site by primer extension, corroborating the previous putative assignment for the alpha-myosin heavy chain promoter based on comparisons between the rat and human genes.

Amino Acid Sequence↗
PubMed1990

Characterization of a functional promoter for the human retinoic acid receptor-alpha (hRAR-alpha).

The three retinoic acid receptors RAR-alpha, beta and gamma are thought to mediate the effects of RA in vivo. We have determined here the exon organisation in the 5' region of the human RAR-alpha (hRAR-alpha) gene, and have identified its promoter. This promoter drives the expression of promoterless beta-globin or CAT reporter genes when transfected into HeLa, Cos-1 or mouse embryonal carcinoma (EC) P19.6 cells in culture. There are no TATA or CCAAT-box elements in this promoter, which appears to belong to the class of promoters made up of an initiator element preceded by several putative binding sites for the transcription factor Sp1. In addition, the hRAR-alpha promoter region contains a number of sequences that are similar to known enhancer elements. Notably, the hRAR-alpha promoter contains a sequence identical to a binding site for the Krox-20 transcription factors, a zinc finger-containing protein which is thought to play a role in the early development of the mouse central nervous system.

Amino Acid Sequence↗
PubMed1990

Molecular cloning of human cardiac troponin I using polymerase chain reaction.

We have used the polymerase chain reaction (PCR) to synthesise a cDNA encoding part of human cardiac troponin I. Amplification was achieved using fully degenerate sets of oligonucleotides corresponding to conserved regions of amino acid sequence identified in other troponin I isoforms. The cloned PCR fragment was subsequently used to isolate full-length cDNAs from a cardiac cDNA library. We describe the approach, as a general cloning strategy starting from limited amino-acid sequence data and report the cloning, and complete amino acid sequence of human cardiac troponin I. Analysis of human development using these clones demonstrates early expression of this gene in the heart.

Amino Acid Sequence↗
PubMed1987

Site-directed mutagenesis reveals transition-state stabilization as a general catalytic mechanism for aminoacyl-tRNA synthetases.

Some aminoacyl-tRNA synthetases of almost negligible homology do have a small region of similarity around four-residue sequence His-Ile(or Leu or Met)-Gly-His(or Asn), the HIGH sequence. The first histidine in this sequence in the tyrosyl-tRNA synthetase, His-45, has been shown to form part of a binding site for the gamma-phosphate of ATP in the transition state for the reaction as does Thr-40. Residue His-56 in the valyl-tRNA synthetase begins a HIGH sequence, and there is a threonine at position 52, one position closer to the histidine than in the tyrosyl-tRNA synthetase. The mutants Thr----Ala-52 and His----Asn-56 have been made and their complete free energy profiles for the formation of valyl adenylate determined. Difference energy diagrams have been constructed by comparison with the reaction of wild-type enzyme. The difference energy profiles are very similar to those for the mutants Thr----Ala-40 and His----Asn-45 of the tyrosyl-tRNA synthetase. Thr-52 and His-56 of the valyl-tRNA synthetase contribute little binding energy to valine, ATP, and Val-AMP. Instead, the wild-type enzyme binds the transition state and pyrophosphate some 6 kcal/mol more tightly than do the mutants. Preferential transition-state stabilization is thus an important component of catalysis by the valyl-tRNA synthetase. Further, by analogy to the tyrosyl-tRNA synthetase, the valyl-tRNA synthetase has a binding site for the gamma-phosphate of ATP in the transition state, and this is likely to be a general feature of aminoacyl-tRNA synthetases that have a HIGH region.

Amino Acid Sequence↗
PubMed1987

The valyl-tRNA synthetase from Bacillus stearothermophilus has considerable sequence homology with the isoleucyl-tRNA synthetase from Escherichia coli.

We report the DNA sequence of the valS gene from Bacillus stearothermophilus and the predicted amino acid sequence of the valyl-tRNA synthetase encoded by the gene. The predicted primary structure is for a protein of 880 amino acids with a molecular mass of 102,036. The molecular mass and amino acid composition of the expressed enzyme are in close agreement with those values deduced from the DNA sequence. Comparison of the predicted protein sequence with known protein sequences revealed a considerable homology with the isoleucyl-tRNA synthetase of Escherichia coli. The two enzymes are identical in some 20-25% of their amino acid residues, and the homology is distributed approximately evenly from N-terminus to C-terminus. There are several regions which are highly conservative between the valyl- and isoleucyl-tRNA synthetases. In one of these regions, 15 of 20 amino acids are identical, and in another, 10 of 14 are identical. The valyl-tRNA synthetase also contains a region HLGH (His-Leu-Gly-His) near its N-terminus equivalent to the consensus HIGH (His-Ile-Gly-His) sequence known to participate in the binding of ATP in the tyrosyl-tRNA synthetase. This is the first example of extensive homology found between two different aminoacyl-tRNA synthetases.

Amino Acid Sequence↗
PubMedDate not supplied

A human retinoic acid receptor which belongs to the family of nuclear receptors.

A cDNA encoding a protein that binds retinoic acid with high affinity has been cloned. The protein is homologous to the receptors for steroid hormones, thyroid hormones and vitamin D3, and appears to be a retinoic acid-inducible trans-acting enhancer factor, suggesting that the molecular mechanisms of the effect of retinoids (vitamin A) on embryonic development, differentiation and tumour cell growth are similar to those described for other members of this nuclear receptor family.

Amino Acid Sequence↗