Interactions of signal peptides with signal-recognition particle.
The mechanisms whereby isolated or synthetic signal peptides inhibit processing of newly synthesized prolactin in microsome-supplemented lysates from reticulocytes and wheat-germ were investigated. At a concentration of 5 microM, a consensus signal peptide reverses the elongation arrest imposed by the signal-recognition particle (SRP), and at higher concentrations in addition inhibits elongation of both secretory and non-secretory proteins. A photoreactive form of a synthetic signal peptide cross-links under u.v. illumination to the 54 kDa and 68 kDa subunits of SRP, whereas the major cross-linked protein produced after photoreaction of rough microsomes is of 45 kDa. As SRP-mediated elongation arrest is unlikely to be essential for translocation, it is suggested that signal peptides may interact with components other than SRP in the translation system in vitro.
Robinson
A
A
Department of Surgery, St. George's Hospital Medical School, Tooting, London, U.K.
Westwood
O M
OM
Austen
B M
BM
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D004285:Dogs; D004591:Electrophoresis, Polyacrylamide Gel; D005914:Globins / Q000235:genetics; D008861:Microsomes / Q000378:metabolism; D008970:Molecular Weight; D010047:Ovalbumin / Q000494:pharmacology; D010179:Pancreas / Q000648:ultrastructure; D010446:Peptide Fragments / Q000494:pharmacology; D011388:Prolactin / Q000096:biosynthesis / Q000378:metabolism; D014176:Protein Biosynthesis / Q000187:drug effects; D011498:Protein Precursors / Q000096:biosynthesis / Q000378:metabolism; D021382:Protein Sorting Signals / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics; D012156:Reticulocytes / Q000378:metabolism; D012261:Ribonucleoproteins / Q000302:isolation & purification / Q000494:pharmacology*; D018271:Signal Recognition Particle; D014908:Triticum; D014466:Ultraviolet Rays
D010446:Peptide Fragments; D011498:Protein Precursors; D021382:Protein Sorting Signals; D012333:RNA, Messenger; D012261:Ribonucleoproteins; D018271:Signal Recognition Particle; C017671:preprolactin; D011388:Prolactin; D005914:Globins; D010047:Ovalbumin