Hi Justin,

I'm not sure if there are papers regarding this for GPCRs, but the phenomenon 
you're referring to is the "positive inside rule". This basically means that 
the SecY translocon (in a way that is only partially clear) mediates membrane 
protein insertion in such a way that the (net) positively charged side of the 
first TM segment stays inside the cytosol. The orientation of the first TM 
dictates that of the subsequent ones (up, down, up etc). People have played 
with this successfully. It's generally valid for membrane proteins. A recent 
reference to get you started is this:

Orientation of small multidrug resistance transporter subunits in the membrane: 
correlation with the positive-inside rule. 

Kolbusz MA, ter Horst R, Slotboom DJ, Lolkema JS.

J Mol Biol. 2010 Sep 10;402(1):127-38.

Good luck, Bert

On 3/4/11 11:31 AM, "Justin Hall" <hallj...@onid.orst.edu> wrote:

Dear Community,

In trying to trouble shoot an experiment I have become interested in
the cellular process that regulates the insertion and proper
orientation of membrane proteins. I am looking for references for how
a GPCR is correctly oriented during expression (i.e. the extra
cellular domain ends up extra cellularly oriented instead of a 50/50
mix in and out), my intuition is that there must be an N-terminal
sequence that directs this process, but I am having no luck finding
information on what this sequence is for GPCRs, what players are
involved or how orientation is thought to be controlled. Any

This is all spurred by my wanting to use phage display with a protein
that binds to the intracellular side of a GPCR, but of course that is
the hard side to present to the outside of a cell so I need to figure
out how to flip these guys around. I have thought about adding a new
TM helix before TM1 (or removing TM1) to flip these guys, but was
hoping there might be another way around that doesn't involve such
massive architectural rearrangement such as simply clipping the
N-terminal sequence responsible for proper orientation (if such a
thing exists). Cheers~


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