Skip to main content
NCBI home page
The Journal of Cell Biology logoLink to The Journal of Cell Biology
. 1985 Jun 1;100(6):1913–1921. doi: 10.1083/jcb.100.6.1913

Elongation arrest is not a prerequisite for secretory protein translocation across the microsomal membrane

PMCID: PMC2113602  PMID: 2581979

Abstract

Signal recognition particle (SRP) is a ribonucleoprotein consisting of six distinct polypeptides and one molecule of small cytoplasmic 7SL RNA. It was previously shown to promote the co-translational translocation of secretory proteins across the endoplasmic reticulum by (a) arresting the elongation of the presecretory nascent chain at a specific point, and (b) interacting with the SRP receptor, an integral membrane protein of the endoplasmic reticulum which is active in releasing the elongation arrest. Recently a procedure was designed by which the particle could be disassembled into its protein and RNA components. We have further separated the SRP proteins into four homogeneous fractions. When recombined with each other and with 7SL RNA, they formed fully active SRP. Particles missing specific proteins were assembled in the hope that some of these would retain some functional activity. SRP(-9/14), the particle lacking the 9-kD and 14- kD polypeptides, was fully active in promoting translocation, but was completely inactive in elongation arrest. This implied that elongation arrest is not a prerequisite for protein translocation. SRP receptor was required for SRP(-9/14)-mediated translocation to occur, and thus must play some role in the translocation process in addition to releasing the elongation arrest.

Full Text

The Full Text of this article is available as a PDF (1.1 MB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Anderson D. J., Mostov K. E., Blobel G. Mechanisms of integration of de novo-synthesized polypeptides into membranes: signal-recognition particle is required for integration into microsomal membranes of calcium ATPase and of lens MP26 but not of cytochrome b5. Proc Natl Acad Sci U S A. 1983 Dec;80(23):7249–7253. doi: 10.1073/pnas.80.23.7249. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Andrews D. W., Walter P., Ottensmeyer F. P. Structure of the signal recognition particle by electron microscopy. Proc Natl Acad Sci U S A. 1985 Feb;82(3):785–789. doi: 10.1073/pnas.82.3.785. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Blobel G., Dobberstein B. Transfer of proteins across membranes. I. Presence of proteolytically processed and unprocessed nascent immunoglobulin light chains on membrane-bound ribosomes of murine myeloma. J Cell Biol. 1975 Dec;67(3):835–851. doi: 10.1083/jcb.67.3.835. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Blobel G., Dobberstein B. Transfer of proteins across membranes. II. Reconstitution of functional rough microsomes from heterologous components. J Cell Biol. 1975 Dec;67(3):852–862. doi: 10.1083/jcb.67.3.852. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Erickson A. H., Blobel G. Cell-free translation of messenger RNA in a wheat germ system. Methods Enzymol. 1983;96:38–50. doi: 10.1016/s0076-6879(83)96007-x. [DOI] [PubMed] [Google Scholar]
  6. Fisher P. A., Berrios M., Blobel G. Isolation and characterization of a proteinaceous subnuclear fraction composed of nuclear matrix, peripheral lamina, and nuclear pore complexes from embryos of Drosophila melanogaster. J Cell Biol. 1982 Mar;92(3):674–686. doi: 10.1083/jcb.92.3.674. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Gilmore R., Blobel G. Transient involvement of signal recognition particle and its receptor in the microsomal membrane prior to protein translocation. Cell. 1983 Dec;35(3 Pt 2):677–685. doi: 10.1016/0092-8674(83)90100-9. [DOI] [PubMed] [Google Scholar]
  8. Gilmore R., Blobel G., Walter P. Protein translocation across the endoplasmic reticulum. I. Detection in the microsomal membrane of a receptor for the signal recognition particle. J Cell Biol. 1982 Nov;95(2 Pt 1):463–469. doi: 10.1083/jcb.95.2.463. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Gilmore R., Walter P., Blobel G. Protein translocation across the endoplasmic reticulum. II. Isolation and characterization of the signal recognition particle receptor. J Cell Biol. 1982 Nov;95(2 Pt 1):470–477. doi: 10.1083/jcb.95.2.470. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Gundelfinger E. D., Krause E., Melli M., Dobberstein B. The organization of the 7SL RNA in the signal recognition particle. Nucleic Acids Res. 1983 Nov 11;11(21):7363–7374. doi: 10.1093/nar/11.21.7363. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Held W. A., Mizushima S., Nomura M. Reconstitution of Escherichia coli 30 S ribosomal subunits from purified molecular components. J Biol Chem. 1973 Aug 25;248(16):5720–5730. [PubMed] [Google Scholar]
  12. Li W. Y., Reddy R., Henning D., Epstein P., Busch H. Nucleotide sequence of 7 S RNA. Homology to Alu DNA and La 4.5 S RNA. J Biol Chem. 1982 May 10;257(9):5136–5142. [PubMed] [Google Scholar]
  13. Lingappa V. R., Devillers-Thiery A., Blobel G. Nascent prehormones are intermediates in the biosynthesis of authentic bovine pituitary growth hormone and prolactin. Proc Natl Acad Sci U S A. 1977 Jun;74(6):2432–2436. doi: 10.1073/pnas.74.6.2432. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Meyer D. I., Krause E., Dobberstein B. Secretory protein translocation across membranes-the role of the "docking protein'. Nature. 1982 Jun 24;297(5868):647–650. doi: 10.1038/297647a0. [DOI] [PubMed] [Google Scholar]
  15. Meyer D. I., Louvard D., Dobberstein B. Characterization of molecules involved in protein translocation using a specific antibody. J Cell Biol. 1982 Feb;92(2):579–583. doi: 10.1083/jcb.92.2.579. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Schulze H., Nierhaus K. H. Minimal set of ribosomal components for reconstitution of the peptidyltransferase activity. EMBO J. 1982;1(5):609–613. doi: 10.1002/j.1460-2075.1982.tb01216.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Steiner D. F., Quinn P. S., Chan S. J., Marsh J., Tager H. S. Processing mechanisms in the biosynthesis of proteins. Ann N Y Acad Sci. 1980;343:1–16. doi: 10.1111/j.1749-6632.1980.tb47238.x. [DOI] [PubMed] [Google Scholar]
  18. Tate W. P., Schulze H., Nierhaus K. H. The Escherichia coli ribosomal protein L11 suppresses release factor 2 but promotes the release factor 1 activities in peptide chain termination. J Biol Chem. 1983 Nov 10;258(21):12816–12820. [PubMed] [Google Scholar]
  19. Ullu E., Murphy S., Melli M. Human 7SL RNA consists of a 140 nucleotide middle-repetitive sequence inserted in an alu sequence. Cell. 1982 May;29(1):195–202. doi: 10.1016/0092-8674(82)90103-9. [DOI] [PubMed] [Google Scholar]
  20. Ullu E., Tschudi C. Alu sequences are processed 7SL RNA genes. Nature. 1984 Nov 8;312(5990):171–172. doi: 10.1038/312171a0. [DOI] [PubMed] [Google Scholar]
  21. Walter P., Blobel G. Disassembly and reconstitution of signal recognition particle. Cell. 1983 Sep;34(2):525–533. doi: 10.1016/0092-8674(83)90385-9. [DOI] [PubMed] [Google Scholar]
  22. Walter P., Blobel G. Preparation of microsomal membranes for cotranslational protein translocation. Methods Enzymol. 1983;96:84–93. doi: 10.1016/s0076-6879(83)96010-x. [DOI] [PubMed] [Google Scholar]
  23. Walter P., Blobel G. Purification of a membrane-associated protein complex required for protein translocation across the endoplasmic reticulum. Proc Natl Acad Sci U S A. 1980 Dec;77(12):7112–7116. doi: 10.1073/pnas.77.12.7112. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Walter P., Blobel G. Signal recognition particle contains a 7S RNA essential for protein translocation across the endoplasmic reticulum. Nature. 1982 Oct 21;299(5885):691–698. doi: 10.1038/299691a0. [DOI] [PubMed] [Google Scholar]
  25. Walter P., Blobel G. Signal recognition particle: a ribonucleoprotein required for cotranslational translocation of proteins, isolation and properties. Methods Enzymol. 1983;96:682–691. doi: 10.1016/s0076-6879(83)96057-3. [DOI] [PubMed] [Google Scholar]
  26. Walter P., Blobel G. Translocation of proteins across the endoplasmic reticulum III. Signal recognition protein (SRP) causes signal sequence-dependent and site-specific arrest of chain elongation that is released by microsomal membranes. J Cell Biol. 1981 Nov;91(2 Pt 1):557–561. doi: 10.1083/jcb.91.2.557. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Walter P., Blobel G. Translocation of proteins across the endoplasmic reticulum. II. Signal recognition protein (SRP) mediates the selective binding to microsomal membranes of in-vitro-assembled polysomes synthesizing secretory protein. J Cell Biol. 1981 Nov;91(2 Pt 1):551–556. doi: 10.1083/jcb.91.2.551. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Walter P., Gilmore R., Blobel G. Protein translocation across the endoplasmic reticulum. Cell. 1984 Aug;38(1):5–8. doi: 10.1016/0092-8674(84)90520-8. [DOI] [PubMed] [Google Scholar]
  29. Walter P., Ibrahimi I., Blobel G. Translocation of proteins across the endoplasmic reticulum. I. Signal recognition protein (SRP) binds to in-vitro-assembled polysomes synthesizing secretory protein. J Cell Biol. 1981 Nov;91(2 Pt 1):545–550. doi: 10.1083/jcb.91.2.545. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Weiner A. M. An abundant cytoplasmic 7S RNA is complementary to the dominant interspersed middle repetitive DNA sequence family in the human genome. Cell. 1980 Nov;22(1 Pt 1):209–218. doi: 10.1016/0092-8674(80)90169-5. [DOI] [PubMed] [Google Scholar]
  31. von Heijne G., Blomberg C. Trans-membrane translocation of proteins. The direct transfer model. Eur J Biochem. 1979 Jun;97(1):175–181. doi: 10.1111/j.1432-1033.1979.tb13100.x. [DOI] [PubMed] [Google Scholar]

Articles from The Journal of Cell Biology are provided here courtesy of The Rockefeller University Press

RESOURCES