bi952575s_si_001.pdf (162.93 kB)
Download fileConformation of a β-Adrenoceptor-Derived Signal Transducing Peptide As Inferred by Circular Dichroism and 1H NMR Spectroscopy†
journal contribution
posted on 1996-05-21, 00:00 authored by Hans Jung, Ralf Windhaber, Dieter Palm, Klaus D. SchnackerzThe peptide T345−359 representing the fourth
intracellular loop of the avian β-adrenoceptor
has been shown to strongly inhibit receptor-mediated adenylate cyclase
activity [Münch, G., Dees, C.,
Hekman, M., & Palm, D. (1991) Eur. J. Biochem. 198,
357−364]. Circular dichroism and two-dimensional
1H NMR techniques were used to investigate the
three-dimensional structure of the peptide in
trifluoroethanol, phospholipid micelles, and small unilamellar
phospholipid vesicles. The prepared vesicles
were tested for size distribution and stability by using electron
microscopy, photon correlation spectroscopy,
and 31P NMR spectroscopy. The peptide T345−359
adopted a predominantly α-helical conformation in
either trifluoroethanol or phospholipid micelles and vesicles. No
structural differences were found for
the conformation of the peptide in the presence of phospholipid
micelles or vesicles, respectively, using
2D 1H NMR techniques, suggesting a unique conformation of
T345−359 when associated with model
membranes. A computer-aided model of the micelle-associated
peptide was derived. The relevance of
the 3D structure of the intracellular loops of receptors to communicate
with the G protein in the signal
transduction cascade is discussed.