%0 Journal Article
%A Lütcke, Henrich
%A High, Stephen
%A Römisch, Karin
%A Ashford, Anthony J.
%A Dobberstein, Bernhard
%D 1992
%F heidok:8555
%J The EMBO Journal
%K GTP binding protein , methionine-rich domain of SRP54 , photo-crosslinking , signal sequence binding , signal recognition particle
%N 4
%P 1543-1551
%R 10.11588/heidok.00008555
%T The methionine-rich domain of the 54 kDa subunit of signal recognition particle is sufficient for the interaction with signal sequences
%U https://archiv.ub.uni-heidelberg.de/volltextserver/8555/
%V 11
%X The signal recognition particle (SRP) binds to signal sequences when they emerge from a translating ribosome and targets the complex of ribosome, nascent chain and SRP to the membrane of the rough endoplasmic reticulum (rER) allowing the co-translational translocation of the nascent chain.  By photo-crosslinking it has been shown that the signal sequence of preprolactin(PPL) only interacts with the methionine-rich (NI) domain of the 54 kDa protein subunit (SRP54) of SRP. Here we show that (i) a signal-anchor sequence is likewise crosslinked only to the methionine-rich domain of SRP54,(ii) free SRP54 can interact with signal sequences independently of the other components of SRP, (iii) its M domain suffices to perform this function, and (iv) an essentially intact M domain is required for signal sequence recognition. Alkylation of the N+G domain in intact SRP54 with N-ethyl maleimide (NE), but not after cleavage with V8 protease, prevents the binding of a signal sequence to the M domain. This suggests a proximity between the N+G and M domains of SRP54 and raises the possibility that the role of the N+G domain may be to regulate the binding and/or the release of signal sequences.