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doi: 10.1002/bies.950100102pmid: 2523701
A stereospecific binding site is not the only determinant governing the selectivity of transport proteins. An understanding of transport across cellular membranes requires a description of the different compartments within a transmembrane channel; evidence for the existence of these compartments comes from the selectivity properties of genetically modified maltoporin. Such compartments may also be of significance in determining the specificity of other transport proteins.
Ruben, Laurens N.; Clothier, Richard H.; Balls, Michael; Horton, John D.
doi: 10.1002/bies.950100103pmid: 2653311
Anuran amphibian metamorphosis is an immunologically interesting period. For the investigator, it provides an unusual opportunity for analyzing both humoral regulation of the immune response and the development and maintenance of self‐tolerance. Some of the questions one can ask are: Why don't immunocompetent larvae destroy antigenically disparate adult cells as they differentiate within them during metamorphosis? Do the dramatic hormonal changes occurring during this period regulate immunological function? How do animals in metamophorsis protect themselves from their immunologically hostile environment?
Smith, Kendric C.; Wang, Tzu‐Chien V.
doi: 10.1002/bies.950100104pmid: 2653307
UV‐radiation‐induced lesions in DNA result in the formation of: (1) excision gaps (i.e. a lesion is excised, leaving a gap), (2) daughter‐strand gaps (i.e. a lesion can be skipped during replication, leaving a gap), and (3) double‐strand breaks (i.e. the DNA strand opposite a gap can be cut). In Escherichia coli, the recA gene product is involved in repairs of all three types of lesions – repair of daughter‐strand gaps (2) and double‐strand breaks (3) constitutes post‐replication repair. The evidence suggests, furthermore, that recA‐dependent repair of excision gaps (1) produced in DNA replicated prior to UV irradiation (pre‐replication repair) appears to occur by similar mechanisms.
Waldman, Scott A.; Murad, Ferid
doi: 10.1002/bies.950100105pmid: 2540738
Atrial natriuretic peptides appear to elicit their actions in some target tissues by binding to a novel cell‐surface transmembrane protein which possesses both peptide binding and guanylate cyclase activities. Ligand binding stimulates enzyme activity to produce increased intracellular concentrations of cyclic GMP which, in turn, mediates the cell's physiological response.
doi: 10.1002/bies.950100106pmid: 2653308
Recent evidence indicates that the presence of serine proteinase inhibitors in plant leaves can reduce predation by insects. Plants can now be transformed with proteinase inhibitor genes with strong promoters to express the inhibitor proteins in relatively high levels at specific times. Inhibitors having variable specificities against digestive proteinases of insects and pathogens can now be assessed for their possible role(s) in natural plant defense and for their potential usefulness in protecting crop plants against herbivores.
doi: 10.1002/bies.950100107pmid: 2653309
This article describes a current view of the events that initiated the transition from the rich organic and inorganic chemistry of the primitive Earth to the earliest forms of life. It is a personal condensation of the basic ideas developed in the so‐called Göttingen school. Most of these will be found in the seminal paper of Eigen1 and the other sources cited. A detailed exposition is given by Küppers2.
doi: 10.1002/bies.950100108pmid: 2653310
In this article, David Shemin, who is now in retirement, describes how in 1944 he ingested 66 g of 15N‐labeled glycine in order to determine the half‐life of hemoglobin and other blood proteins. The ramifications of the experiment led to the unravelling of the biosynthesis of porphyrins and the role of glycine and α‐aminolevulinic acid in heme, vitamin B12 and chlorophyll synthesis.
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