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  • cytoplasmic residues  (1)
  • lipid vesicles  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Thermal stability ofTorpedo californica acetylcholine receptor in a cholesterol lipid environment (1994)
    Springer
    Molecular and cellular biochemistry 132 (1994), S. 91-99 
    Details
    ISSN: 1573-4919
    Keywords: cholesterol ; lipid vesicles ; thermal stability ; acetylcholine receptor ; α-Bgtx ; Na+ efflux
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Controlled heating of acetylcholine receptor (AChR) vesicles inactivates the α-bungarotoxin (α-Bgtx) binding sites with a T50 (temperature at which 50% of the initial capacity to bind α-Bgtx remains) of 60±0.2°C. The same value was obtained for receptor reconstituted in lipid vesicles fromTorpedo electroplax where the % mol composition of cholesterol to phospholipid was 30. However, when the reconstitution was carried out in dioleoylphosphatidylcholine (DOPC), dioleoylphosphatidic acid (DOPA) vesicles (3:1 molar ratio), T50 of the curves decreased to 56±0.2° C and no carbamylcholine stimulated22Na+ flux was detected. Inclusion of cholesterol in the DOPC-DOPA vesicles increased the toxin binding site stability. The maximal T50 of the toxin binding curves was 63±0.1° C when the % mol cholesterol/mol DOPC:DOPA in the vesicles was 33. Under these conditions AChR was able to translocate ions, a property that was lost upon heating at 46° C. Preincubation of AChR in the presence of d-tubocurarine, tetracaine or procaine did not affect T50 values of toxin binding. However, a slight increment in thermal stability was found when the receptor was preincubated in the presence of carbamylcholine. The results show that cholesterol requirements for protecting against thermal inactivation of toxin binding and ion gating properties are different and the carbamylcholine-bound receptor may have a different conformation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00926917
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Residues 377-389 from the δ subunit ofTorpedo californica acetylcholine receptor are located in the cytoplasmic surface (1994)
    Springer
    The protein journal 13 (1994), S. 67-76 
    Details
    ISSN: 1573-4943
    Keywords: Acetylcholine receptor ; cytoplasmic residues ; fluorophore insertion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Torpedo californica acetylcholine receptor (AcChR) enriched, sealed vesicles have been specifically labeled on the cytoplasmic surface with pyridoxal 5′-phosphate (Perez-Ramirez, B., and Martinez-Carrion, M., 1989,Biochemistry 28, 5034–5040). After chromatography of the peptide fragments produced by tryptin digestion of labeled AcChR, several fractions containing the phosphopyridoxyl label were obtained. Edman degradation identified one of the fractions, with sequence SRSELMFEKQSER, as corresponding to residues 377–389 in theδ subunit (primary structure). The latter must be a cytoplasmic region of this transmembranous protein, and residueδK385 must reside in a water-soluble exposed domain of the cytosolic side of the membrane. Introduction of phosphopyridoxyl residues allows for their potential use as probes of conformational changes in the cytosolic surface of the receptor molecule.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01891994
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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