Ho,
A second the vote for OmpF, but many porins could do. Although it is a little harder to purify from native membranes, OmpF has the advantage that it can be crystallized in about 1-2 hours from a simple detergent solution with different PEGs AND (!!!) it is as stable as a rock (you can drop it on the floor, scrap it up, and it is still alive). Over 25 years ago we used it in one of the first EMBO courses on membrane protein crystallization and it worked like a charm. "Assaying" it is a problem, but you can very it is there by a gel shift assay (Unheated in SDS it is a trimer, heated it is a monomer). However, other porins (LamB, OmpC, etc.) and porin-like proteins (EstA) could work nicely.
Cheers,
Michael
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R. Michael Garavito, Ph.D.
Professor of Biochemistry & Molecular Biology
Michigan State University
East Lansing, MI 48824-1319
Office: (517) 355-9724 Lab: (517) 353-9125
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On Sep 11, 2012, at 6:09 PM, Toufic El Arnaout wrote:
Hi,Just for info if you were to use the LCP method (a course by itself), check this about OmpF ("membrane lysozyme"):
bR protein sometimes takes weeks to give crystals and people prefer the dark (depends on the conf state).. but good idea for spectro assays (check reaction centres/light-harvesting complexes too).
Beta barrels are very stable too.
If you want to use the GFP fusion and you want to cleave it, it might add extra time and steps to the students than going directly with a GFP free his-tagged protein to trials.
Regards
Toufic El Arnaout
Membrane Structural and Functional Biology Group
Trinity College Dublin
On Tue, Sep 11, 2012 at 10:18 PM, Ho Leung Ng
<[log in to unmask]> wrote:
Hello,
I am developing an undergraduate biochemistry lab class and
would like to incorporate experiments with membrane proteins. Does
anyone have suggestions on membrane proteins that are relatively easy
to express, purify, and assay? Bonus points for crystallizable! At the
moment, my leading candidate is aquaporin AqpZ from E. coli. I am
planning to express the membrane protein as a GFP fusion so students
can easily follow it through the course of the labs.
Thank you,
Ho
Ho Leung Ng
University of Hawaii at Manoa
Assistant Professor, Department of Chemistry
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