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  • 1
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 7253-7259 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: Proteins change their global conformation very slowly compared to the time scales of most localized internal motion. The relationship between these slow and fast processes was investigated with the aid of a stochastic model recently applied to a related problem of protein folding [Zwanzig et al., Proc. Natl. Acad. Sci. 89, 20 (1992)]. In the present study a change in conformation was treated as a bond rotational isomerization that may only occur when several other gating bonds simultaneously assume permissive orientations. The requirement of correct orientation of these gating bonds is analogous to the alignment of the tumblers in a lock. For a range of reasonable choices of parameters, this model generated realistic time scales for protein conformational changes. Although the transition time depended on the value of an energy bias against the permissive position of a gating bond, the model could still generate reasonable transition times in the absence of an energy bias. For a wide range of parameters chosen to give typical experimental rates for biological transitions, the model predicted conformational changes with simple exponential kinetics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 91 (1987), S. 3621-3624 
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie , Physik
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Biochemistry 15 (1976), S. 2555-2561 
    ISSN: 1520-4995
    Quelle: ACS Legacy Archives
    Thema: Biologie , Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Biochemistry 17 (1978), S. 4470-4474 
    ISSN: 1520-4995
    Quelle: ACS Legacy Archives
    Thema: Biologie , Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Biochemistry 17 (1978), S. 911-915 
    ISSN: 1520-4995
    Quelle: ACS Legacy Archives
    Thema: Biologie , Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neuroendocrinology 6 (1994), S. 0 
    ISSN: 1365-2826
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Neuroactive steroid modulation of GABAA receptors was investigated in the peptidergic nerve terminals of the posterior pituitary using patch clamp techniques. In common with GABAA receptors in cell bodies, the nerve terminal GABAA receptor was potentiated by the synthetic steroid alphaxalone and by physiological concentrations of the progesterone metabolite allopregnanolone. Both of these agents enhanced Cl− currents elicited by GABA. Estradiol-17β had a weak inhibitory effect on GABA responses of nerve terminals, but only at high concentrations. The potentiating action was manifest as an increase in the probability of channel opening, with no effect on the rate of desensitization of the GABAA receptor. Neuroactive steroids enhanced GABA-gated Cl∼ channel activity in cell-free membrane patches, thus demonstrating a membrane delimited response. These results indicated that with regard to allosteric modulation by neuroactive steroids, the nerve terminal GABAA receptor is similar to the GABAA receptors of nerve cell bodies and endocrine cells. Neuroactive steroids are thus capable of altering the chemosensitivity of nerve terminal membranes by enhancing GABA inhibition at this location. The neuroactive steroid sensitivity of nerve terminal GABAA receptors provides a pathway by which gonadal steroid derivatives could regulate peptide secretion from neurosecretory neurons. Such a pathway could participate in the coordination of neuropeptide secretion during complex neuroendocrine functions. With specific regard to the neurohypophysis, neuroactive steroid-induced changes in the sensitivity of nerve terminal GABAA receptors could play a role in the initiation of oxytocin secretion during the transition between pregnancy and parturition.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 282 (1979), S. 863-864 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] The methods used for single-channel recording have been described by Neher et a/.8. A small (-1 ??2) patch of cell surface is isolated with a specially fabricated extracellular glass microelectrode. A low-noise circuit amplifies the current through this patch of membrane. The signal is then ...
    Materialart: Digitale Medien
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  • 8
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Exocytosis—the release of the contents of a vesicle—proceeds by two mechanisms. Full fusion occurs when the vesicle and plasma membranes merge. Alternatively, in what is termed kiss-and-run, vesicles can release transmitter during transient contacts with the plasma membrane. Little ...
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    [s.l.] : Macmillian Magazines Ltd.
    Nature 418 (2002), S. 89-92 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] The vesicles that package neurotransmitters fall into two distinct classes, large dense-core vesicles (LDCVs) and small synaptic vesicles, the coexistence of which is widespread in nerve terminals. High resolution capacitance recording reveals unitary steps proportional to vesicle size. ...
    Materialart: Digitale Medien
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  • 10
    ISSN: 1432-2013
    Schlagwort(e): Acetylcholine receptor ; Xenopus oocyte ; single ; channel
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract During the development of mammalian muscle the γ-subunit of the nicotinic acetylcholine receptor (AChR) is replaced by the ɛ-subunit to produce well-defined alterations in the conductance and gating of the channel. To gain a better unterstanding of the functional role of the γ and ɛ-subunits, we have studied the properties of an AChR channel lacking these subunits. The AChR expressed in Xenopus oocytes injected with the bovine α-, β and δ-subunit-specific mRNAs (referred to as αβδ-AChR) is unusual in that its channel opens spontaneously at a high frequency in the absence of agonist. From a comparison of the αβδ-AChR with complete receptors containing either the γ or ɛ-subunit, we conclude that the γ and ɛ-subunits influence most channel properties, including agonist binding, and are especially important for stabilizing the closed state of the unliganded receptor channel. The αβδ-AChR can form when a complete set of four subunit-specific mRNAs is injected. The ease with which it is assembled raises the possibility that the αβδ- AChR contributes to some of the variations in receptor properties that occur during development.
    Materialart: Digitale Medien
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