experimentally evidenced signal anchor proteins

Hello everybody,

I am trying to create a dataset of signal anchor proteins of the type
II. These are proteins which posses a signal peptide but which will be
retained in the ER membrane due to a lacking cleavage site. I have
already done some SRS searches on SwissProt and applied some own
parsers. But apparently there are not that many proteins with a high
confidence for being a real signal anchor ;-(

Does anybody of you know a database where I could find these kind of
proteins? Or even better, does anybody work on this subject and like
to help me out a bit?

Thank you very much in advance,
cu
Ben