Transfection/electroporation protocols

[Mayumi Yagi]

Hi, netters,

I'd like to get a feel for people's expereinces getting high-level 
protein secretion from transfected cell lines.  We are trying to express 
the extracellular domain of a cell surface receptor in quantities 
sufficient to run binding assays.  In our ultimate dream of dreams, we'd 
like to get quantities sufficient for x-ray crystallography (10-15mg of 
purified proteins).  Given the number of possibilities out there, I'd 
like to know what are peoples' favorite cell lines and protocols 
(briefly, of course!).  I've started out with transient transfections of 
a variety of lines, and so far haven't gotten any detectable secretion of 
protein even though there is a signal sequence left on it.
Thanks, all.