Biomaterial Database

Photocrosslinking of the signal sequence of nascent preprolactin to the 54-kilodalton polypeptide of the signal recognition particle. 1986

U C Krieg, and P Walter, and A E Johnson

Photoreactive moieties were incorporated into nascent polypeptides in a wheat germ protein-synthesizing system by using a plasmid-derived preprolactin mRNA and a Lys-tRNA analog, N epsilon-(5-azido-2-nitrobenzoyl)-Lys-tRNA (epsilon ANB-Lys-tRNA). The presence of the abnormally large amino acid side chains in the nascent chains did not impair function: complete preprolactin chains were synthesized in the absence of the signal recognition particle (SRP), elongation was arrested in the presence of SRP, and SRP-dependent translocation across the membrane of the endoplasmic reticulum and signal peptidase cleavage were observed in the presence of salt-extracted microsomes. Photolysis of elongation-arrested ribosomes resulted in several light- and epsilon ANB-Lys-tRNA-dependent crosslinks. By using antibodies specific for each of the proteins, one covalent complex was shown to be a photocrosslink between the preprolactin nascent chain and the 54-kDa protein subunit of SRP. This demonstrates that the N-terminal end of a secretory protein is located adjacent to the SRP in elongation-arrested ribosomes and strongly suggests that the signal sequence is recognized by and binds to the 54-kDa subunit of SRP. The other photocrosslinks involve as-yet-unidentified proteins in the large ribosomal subunit, indicating that this method of incorporating probes provides a powerful approach to examining the environment and interactions of the nascent chain during translation and translocation across the membrane of the endoplasmic reticulum. The Lys-tRNA analog also successfully photoaffinity-labeled the Escherichia coli elongation factor Tu (EF-Tu) in the epsilon ANB-Lys-tRNA.EF-Tu.GTP ternary complex.

UI	MeSH Term	Description	Entries
D008027	Light	That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.	Light, Visible,Photoradiation,Radiation, Visible,Visible Radiation,Photoradiations,Radiations, Visible,Visible Light,Visible Radiations
D008239	Lysine	An essential amino acid. It is often added to animal feed.	Enisyl,L-Lysine,Lysine Acetate,Lysine Hydrochloride,Acetate, Lysine,L Lysine
D010444	Peptide Elongation Factor Tu	A protein found in bacteria and eukaryotic mitochondria which delivers aminoacyl-tRNA's to the A site of the ribosome. The aminoacyl-tRNA is first bound to a complex of elongation factor Tu containing a molecule of bound GTP. The resulting complex is then bound to the 70S initiation complex. Simultaneously the GTP is hydrolyzed and a Tu-GDP complex is released from the 70S ribosome. The Tu-GTP complex is regenerated from the Tu-GDP complex by the Ts elongation factor and GTP.	Elongation Factor Tu,EF-Tu,Eucaryotic Elongation Factor Tu,Protein Synthesis Elongation Factor Tu,eEF-Tu,EF Tu,Factor Tu, Elongation,eEF Tu
D011388	Prolactin	A lactogenic hormone secreted by the adenohypophysis (PITUITARY GLAND, ANTERIOR). It is a polypeptide of approximately 23 kD. Besides its major action on lactation, in some species prolactin exerts effects on reproduction, maternal behavior, fat metabolism, immunomodulation and osmoregulation. Prolactin receptors are present in the mammary gland, hypothalamus, liver, ovary, testis, and prostate.	Lactogenic Hormone, Pituitary,Mammotropic Hormone, Pituitary,Mammotropin,PRL (Prolactin),Hormone, Pituitary Lactogenic,Hormone, Pituitary Mammotropic,Pituitary Lactogenic Hormone,Pituitary Mammotropic Hormone
D011498	Protein Precursors		Precursors, Protein
D006160	Guanosine Triphosphate	Guanosine 5'-(tetrahydrogen triphosphate). A guanine nucleotide containing three phosphate groups esterified to the sugar moiety.	GTP,Triphosphate, Guanosine
D000345	Affinity Labels	Analogs of those substrates or compounds which bind naturally at the active sites of proteins, enzymes, antibodies, steroids, or physiological receptors. These analogs form a stable covalent bond at the binding site, thereby acting as inhibitors of the proteins or steroids.	Affinity Labeling Reagents,Labeling Reagents, Affinity,Labels, Affinity,Reagents, Affinity Labeling
D012346	RNA, Transfer, Amino Acyl	Intermediates in protein biosynthesis. The compounds are formed from amino acids, ATP and transfer RNA, a reaction catalyzed by aminoacyl tRNA synthetase. They are key compounds in the genetic translation process.	Amino Acyl tRNA,Transfer RNA, Amino Acyl,tRNA-Amino Acyl,Amino Acyl T RNA,Acyl tRNA, Amino,Acyl, tRNA-Amino,tRNA Amino Acyl,tRNA, Amino Acyl
D014176	Protein Biosynthesis	The biosynthesis of PEPTIDES and PROTEINS on RIBOSOMES, directed by MESSENGER RNA, via TRANSFER RNA that is charged with standard proteinogenic AMINO ACIDS.	Genetic Translation,Peptide Biosynthesis, Ribosomal,Protein Translation,Translation, Genetic,Protein Biosynthesis, Ribosomal,Protein Synthesis, Ribosomal,Ribosomal Peptide Biosynthesis,mRNA Translation,Biosynthesis, Protein,Biosynthesis, Ribosomal Peptide,Biosynthesis, Ribosomal Protein,Genetic Translations,Ribosomal Protein Biosynthesis,Ribosomal Protein Synthesis,Synthesis, Ribosomal Protein,Translation, Protein,Translation, mRNA,mRNA Translations
D021382	Protein Sorting Signals	Amino acid sequences found in transported proteins that selectively guide the distribution of the proteins to specific cellular compartments.	Leader Signal Peptides,Leader Peptide,Leader Sequences, Peptide,Peptide Leader Sequences,Peptide Signal Sequences,Signal Peptide,Signal Peptides,Signal Sequence, Peptide,Signal Sequences,Signal Sequences, Peptide,Leader Peptides,Leader Sequence, Peptide,Leader Signal Peptide,Peptide Leader Sequence,Peptide Signal Sequence,Peptide, Leader,Peptide, Leader Signal,Peptide, Signal,Peptides, Leader,Peptides, Leader Signal,Peptides, Signal,Protein Sorting Signal,Sequence, Peptide Leader,Sequence, Peptide Signal,Sequence, Signal,Sequences, Peptide Leader,Sequences, Peptide Signal,Sequences, Signal,Signal Peptide, Leader,Signal Peptides, Leader,Signal Sequence,Signal, Protein Sorting,Signals, Protein Sorting,Sorting Signal, Protein,Sorting Signals, Protein