In article <2aro4j$fhl at apakabar.cc.columbia.edu> jhj4 at konichiwa.cc.columbia.edu (Jeffrey Hall Jennings) writes:
>In article <klingler.751858238 at cmgm.stanford.edu>,
>Tod Klingler <klingler at cmgm.stanford.edu> wrote:
>>ladasky at netcom.com (John J. Ladasky II) writes:
>>>>> Am told that the crystallline structure of an MHC class II
>>>molecule has just been determined. By whom? Where was it published?
>>>>Don Wiley at Harvard. Check out the 1 July 1993 Nature, 364:33-39.
>>How is it possible to do xray crystall. on a membrane-bound protien?
>
One can easily do xray crystallography on a membrane bound protein
if one either a) cleaves it from the cell surface or b) makes
a genetic construct of the soluble portion of the molecule. Both
of these techniques were used in the structure determination of
MHC class I and class II.
In addition, recent progress has also
seen the structure determination of the photosynthetic reaction
center and several bacterial porins, all of which are integral
membrane proteins. The molecules were crystallized in the presence
of lipids and/or detergents. The other major breakthroughs
in membrane protein biophysics involve the use of electron
diffraction on two-dimensional crystals, such as the
low resolution structure of rhodopsin (Schertler GF; Villa C; Henderson R
Nature 362:770 (1993)). Such work is to say the least difficult,
but more and more membrane protein structures are being determined
all of the time.
daved h fremont at scripps.edu
--
<daved h fremont> fremont at scripps.edu
