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A complex of the signal sequence binding protein and the SRP RNA promotes translocation of nascent proteins.
Author(s) -
Hauser S.,
Bacher G.,
Dobberstein B.,
Lütcke H.
Publication year - 1995
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1995.tb00235.x
Subject(s) - signal recognition particle , signal recognition particle receptor , signal recognition particle rna , biology , chromosomal translocation , signal peptide , protein targeting , rna , microbiology and biotechnology , rna binding protein , ribonucleoprotein , endoplasmic reticulum , translocon , gtpase , cytoplasm , ribosome , peptide sequence , biochemistry , membrane protein , gene , membrane
Translocation of proteins across the endoplasmic reticulum membrane is initiated by the signal recognition particle (SRP), a cytoplasmic ribonucleoprotein complex consisting of a 7S RNA and six polypeptides. To investigate the functions of the SRP components, we have tested the activities of several SRP subparticles. We show that the SRP GTPase (SRP54) alone binds a signal sequence and discriminates it from a non‐signal sequence. Although SRP54 alone is unable to promote translocation, SRP54 in a complex with SRP RNA is both necessary and sufficient to promote translocation of an elongation‐arrested nascent protein in a GTP‐regulated manner. For co‐translational translocation, additional SRP components are required. We discuss the implications of our results for the function of the Escherichia coli SRP which is homologous to the SRP54/SRP‐RNA complex.