Anti-pp60src antibodies are substrates for EGF-stimulated protein kinase

Epidermal growth factor (EGF) stimulates phosphorylation of its own receptor at a tyrosine residue. Similarly, the viral gene product pp60src, which is responsible for cellular transformation by avian sarcoma virus (ASV), phosphorylates itself and immunoglobulin directed against pp60src at tyrosine residues. This unusual site of phosphorylation catalysed by two membrane-associated protein kinases involved in growth control prompted us to study the immunological relatedness of the EGF-stimulated protein kinase and the pp60src. Using anti-pp60src antisera, we attempted to immunoprecipitate the EGF-stimulated protein kinase solubilized from plasma membranes. We report here that neither the EGF-stimulated kinase nor the EGF receptor were immunoprecipitable by anti-pp60src sera. However, anti-pp60src IgG served as a specific substrate for the EGF-stimulated kinase, suggesting a close similarity between the EGF-stimulated kinase and pp60src.     

The role of muscle in determining growth and size in teleost fish

Summary Rapid growth to large size in fish results from a sustained recruitment of new fibres into their axial series of myomeres. Cessation of recruitment at a small fish size leads to slow growth and a small final size of the fish. Fibre growth dynamics of fishes evidently govern growth and size through fibres' surface area to length ratios, which control their nutrient assimilation rates.     

Trapped antihydrogen

Antimatter was first predicted in 1931, by Dirac. Work with high-energy antiparticles is now commonplace, and anti-electrons are used regularly in the medical technique of positron emission tomography scanning. Antihydrogen, the bound state of an antiproton and a positron, has been produced at low energies at CERN (the European Organization for Nuclear Research) since 2002. Antihydrogen is of interest for use in a precision test of nature's fundamental symmetries. The charge conjugation/parity/time reversal (CPT) theorem, a crucial part of the foundation of the standard model of elementary particles and interactions, demands that hydrogen and antihydrogen have the same spectrum. Given the current experimental precision of measurements on the hydrogen atom (about two parts in 10(14) for the frequency of the 1s-to-2s transition), subjecting antihydrogen to rigorous spectroscopic examination would constitute a compelling, model-independent test of CPT. Antihydrogen could also be used to study the gravitational behaviour of antimatter. However, so far experiments have produced antihydrogen that is not confined, precluding detailed study of its structure. Here we demonstrate trapping of antihydrogen atoms. From the interaction of about 10(7) antiprotons and 7?×?10(8) positrons, we observed 38 annihilation events consistent with the controlled release of trapped antihydrogen from our magnetic trap; the measured background is 1.4?±?1.4 events. This result opens the door to precision measurements on anti-atoms, which can soon be subjected to the same techniques as developed for hydrogen.     

Volume-regulated chloride channels associated with the human multidrug-resistance P-glycoprotein.

Expression of P-glycoprotein, the product of the MDR1 gene, confers multidrug resistance on cell lines and human tumours (reviewed in refs 1,2). P-glycoprotein (relative molecular mass 170,000) is an ATP-dependent, active transporter which pumps hydrophobic drugs out of cells, but its normal physiological role is unknown. It is a member of the ABC (ATP-binding cassette) superfamily of transporters, which includes many bacterial transport systems, the putative peptide transporter from the major histocompatibility locus, and the product of the cystic fibrosis gene (the cystic fibrosis transmembrane regulator, CFTR). CFTR is located in the apical membranes of many secretory epithelia and is associated with a cyclic AMP-regulated chloride channel. At least two other chloride channels are present in epithelial cells, regulated by cell volume and by intracellular Ca2+, respectively. Because of the structural and sequence similarities between P-glycoprotein and CFTR, and because P-glycoprotein is abundant in many secretory epithelia, we examined whether P-glycoprotein might be associated with one or other of these channels. We report here that expression of P-glycoprotein generates volume-regulated, ATP-dependent, chloride-selective channels, with properties similar to channels characterized previously in epithelial cells.     

Characteristics of mosaic muscle growth in rainbow troutSalmo gairdneri

Summary There are 4 stages in the growth of mosaic (axial) muscle, which is the predominating tissue in trout; the stages are distinguishable by the modal values and range of their fibre diameters over the size range 2.3 to 50+cm fork length. Up to 50 cm, most of the increase in mosaic muscle is attributable to continuous recruitment of new fibers. Beyond 50 cm, further growth is a result of increase in diameter of existing fibers.     

Enzyme variability in local populations ofDrosophila species

Summary Dimeric acid phosphatases are coded by allelic variants of a single autosomal gene. Esterases have revealed allelic as well as non-allelic polymorphism. Allelic frequencies and proportion of heterozygosity at the polymorphic loci have been described.     

Structural model of ATP-binding proteins associated with cystic fibrosis, multidrug resistance and bacterial transport

The ATP-binding cassette (ABC) superfamily of transport systems now includes over thirty proteins that share extensive sequence similarity and domain organization. This superfamily includes the well characterized periplasmic binding protein-dependent uptake systems of prokaryotes, bacterial exporters, and eukaryotic proteins including the P-glycoprotein associated with multidrug resistance in tumours (MDR), the STE6 gene product that mediates export of yeast a-factor mating pheromone, pfMDR that is implicated in chloroquine resistance of the malarial parasite, and the product of the cystic fibrosis gene (CFTR). Here we present a tertiary structure model of the ATP-binding cassettes characteristic of this class of transport system, based on similarities between the predicted secondary structures of members of this family and the previously determined structure of adenylate kinase. This model has implications for both the molecular basis of transport and cystic fibrosis and provides a framework for further experimentation.