%0 Journal Article
%A Lütcke, Henrich
%A Prehn, Siegfried
%A Ashford, Anthony J.
%A Remus, Michael
%A Frank, Rainer
%A Dobberstein, Bernhard
%D 1993
%F heidok:8581
%J The Journal of Cell Biology
%N 5
%P 977-985
%R 10.11588/heidok.00008581
%T Assembly of the 68- and 72-kD Proteins of Signal Recognition Particle with 7S RNA
%U https://archiv.ub.uni-heidelberg.de/volltextserver/8581/
%V 121
%X Signal recognition particle (SRP), the cytoplasmic ribonucleoprotein particle that mediates the targeting of proteins to the ER, consists of a 7S RNA and six different proteins. The 68- (SRP68) and 72-(SRP72) kD proteins of SRP are bound to the 7S RNA of SRP as a heterodimeric complex (SRP68/72). Here we describe the primary structure of SRP72 and the assembly of SRP68, SRP72 and 7S RNA into a ribonucleoprotein particle.  The amino acid sequence deduced from the cDNA of SRP72 reveals a basic protein of 671 amino acids which shares no sequence similarity with any protein in the sequence data libraries. Assembly of SRP72 into a ribonucleoprotein particle required the presence of 7S RNA and SRP68. In contrast, SRP68 alone specifically bound to 7S RNA. SRP68 contacts the 7S RNA via its NH2-terminal half while COOH-terminal portions of SRP68 and SRP72 are in contact with each other in SRP. SRP68 thus serves as a link between 7S RNA and SRP72. As a large NH2-terminal domain of SRP72 is exposed on SRP it may be a site of contact to other molecules involved in the SRP cycle between the ribosome and the ER membrane.