[ off topic ]
cute... evolution.... whatever works......
Biochemistry 1999 Apr 20;38(16):4905-11
Internal dynamics of the nicotinic acetylcholine receptor in reconstituted
membranes.
Baenziger JE, Darsaut TE, Morris ML
Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5.
[Medline record in process]
The structure and 1H/2H exchange kinetics of affinity-purified nAChR reconstituted into egg phosphatidylcholine membranes
with increasing levels of either dioleoylphosphatidic acid (DOPA) or cholesterol (Chol) have been examined using infrared
spectroscopy. All spectra of the reconstituted nAChR membranes recorded after 72 h in 2H2O exhibit comparable amide I
band shapes, suggesting a similar secondary structure for the nAChR in each lipid environment. Increasing levels of either
DOPA or Chol, however, lead to an increasing intensity of the amide II band, indicating a decreasing proportion of nAChR
peptide hydrogens that have exchanged for deuterium. Spectra recorded as a function of time after exposure of the nAChR to
2H2O show that the presence of either lipid slows down the 1H/2H exchange of those peptide hydrogens that normally
exchange on the minutes to hours time scale. The slowing of peptide 1H/2H exchange correlates with both an increasing ability
of the nAChR to undergo agonist-induced conformational change [Baenziger, J. E., Morris, M.-L., Darsaut, T. E., and Ryan,
S. E. (1999) in preparation] and possibly a decreasing membrane fluidity. Our data suggest that lipid composition dependent
changes in nAChR peptide 1H/2H exchange kinetics reflect altered internal dynamics of the nAChR. Lipids may influence
protein function by changing the internal dynamics of integral membrane proteins.
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tons of new stuff out on nAChRs, BTW. I haven't seen much of Abbott's program lately. Anyone know the status? |
