Skip to main content
PMC home page
Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1980 Mar;77(3):1496–1500. doi: 10.1073/pnas.77.3.1496

Intracellular protein topogenesis

Günter Blobel 1
PMCID: PMC348522  PMID: 6929499

Abstract

Concurrently with or shortly after their synthesis on ribosomes, numerous specific proteins are unidirectionally translocated across or asymmetrically integrated into distinct cellular membranes. Thereafter, subpopulations of these proteins need to be sorted from each other and routed for export or targeted to other intracellular membranes or compartments. It is hypothesized here that the information for these processes, termed “protein topogenesis,” is encoded in discrete “topogenic” sequences that constitute a permanent or transient part of the polypeptide chain. The repertoire of distinct topogenic sequences is predicted to be relatively small because many different proteins would be topologically equivalent—i.e., targeted to the same intracellular address. The information content of topogenic sequences would be decoded and processed by distinct effectors. Four types of topogenic sequences could be distinguished: signal sequences, stop-transfer sequences, sorting sequences, and insertion sequences. Signal sequences initiate translocation of proteins across specific membranes. They would be decoded and processed by protein translocators that, by virtue of their signal sequence-specific domain and their unique location in distinct cellular membranes, effect unidirectional translocation of proteins across specific cellular membranes. Stop-transfer sequences interrupt the translocation process that was previously initiated by a signal sequence and, by excluding a distinct segment of the polypeptide chain from translocation, yield asymmetric integration of proteins into translocation-competent membranes. Sorting sequences would act as determinants for posttranslocational traffic of subpopulations of proteins, originating in translocation-competent donor membranes (and compartments) and going to translocation-incompetent receiver membranes (and compartments). Finally, insertion sequences initiate unilateral integration of proteins into the lipid bilayer without the mediation of a distinct protein effector. Examples are given for topogenic sequences, either alone or in combination, to provide the information for the location of proteins in any of the intracellular compartments or for the asymmetric orientation of proteins and their location in any of the cellular membranes. Proposals are made concerning the evolution of topogenic sequences and the relationship of protein topogenesis to the precellular evolution of membranes and compartments.

Keywords: protein translocation across membranes, protein integration into membranes, posttranslocational sorting, topogenic sequences, phylogeny of membranes and compartments

Full text

PDF
1499

Selected References

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

  1. 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]
  2. 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]
  3. Blobel G., Walter P., Chang C. N., Goldman B. M., Erickson A. H., Lingappa V. R. Translocation of proteins across membranes: the signal hypothesis and beyond. Symp Soc Exp Biol. 1979;33:9–36. [PubMed] [Google Scholar]
  4. Chang C. N., Model P., Blobel G. Membrane biogenesis: cotranslational integration of the bacteriophage f1 coat protein into an Escherichia coli membrane fraction. Proc Natl Acad Sci U S A. 1979 Mar;76(3):1251–1255. doi: 10.1073/pnas.76.3.1251. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Chua N. H., Schmidt G. W. Post-translational transport into intact chloroplasts of a precursor to the small subunit of ribulose-1,5-bisphosphate carboxylase. Proc Natl Acad Sci U S A. 1978 Dec;75(12):6110–6114. doi: 10.1073/pnas.75.12.6110. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Dobberstein B., Blobel G., Chua N. H. In vitro synthesis and processing of a putative precursor for the small subunit of ribulose-1,5-bisphosphate carboxylase of Chlamydomonas reinhardtii. Proc Natl Acad Sci U S A. 1977 Mar;74(3):1082–1085. doi: 10.1073/pnas.74.3.1082. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Edelman G. M. Surface modulation in cell recognition and cell growth. Science. 1976 Apr 16;192(4236):218–226. doi: 10.1126/science.769162. [DOI] [PubMed] [Google Scholar]
  8. Goldman B. M., Blobel G. Biogenesis of peroxisomes: intracellular site of synthesis of catalase and uricase. Proc Natl Acad Sci U S A. 1978 Oct;75(10):5066–5070. doi: 10.1073/pnas.75.10.5066. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Lin J. J., Kanazawa H., Ozols J., Wu H. C. An Escherichia coli mutant with an amino acid alteration within the signal sequence of outer membrane prolipoprotein. Proc Natl Acad Sci U S A. 1978 Oct;75(10):4891–4895. doi: 10.1073/pnas.75.10.4891. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Lingappa V. R., Katz F. N., Lodish H. F., Blobel G. A signal sequence for the insertion of a transmembrane glycoprotein. Similarities to the signals of secretory proteins in primary structure and function. J Biol Chem. 1978 Dec 25;253(24):8667–8670. [PubMed] [Google Scholar]
  11. Lingappa V. R., Lingappa J. R., Blobel G. Chicken ovalbumin contains an internal signal sequence. Nature. 1979 Sep 13;281(5727):117–121. doi: 10.1038/281117a0. [DOI] [PubMed] [Google Scholar]
  12. Maccecchini M. L., Rudin Y., Blobel G., Schatz G. Import of proteins into mitochondria: precursor forms of the extramitochondrially made F1-ATPase subunits in yeast. Proc Natl Acad Sci U S A. 1979 Jan;76(1):343–347. doi: 10.1073/pnas.76.1.343. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Novikoff A. B. The endoplasmic reticulum: a cytochemist's view (a review). Proc Natl Acad Sci U S A. 1976 Aug;73(8):2781–2787. doi: 10.1073/pnas.73.8.2781. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Palade G. Intracellular aspects of the process of protein synthesis. Science. 1975 Aug 1;189(4200):347–358. doi: 10.1126/science.1096303. [DOI] [PubMed] [Google Scholar]
  15. Schmidt G. W., Devillers-Thiery A., Desruisseaux H., Blobel G., Chua N. H. NH2-terminal amino acid sequences of precursor and mature forms of the ribulose-1,5-bisphosphate carboxylase small subunit from Chlamydomonas reinhardtii. J Cell Biol. 1979 Dec;83(3):615–622. doi: 10.1083/jcb.83.3.615. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from Proceedings of the National Academy of Sciences of the United States of America are provided here courtesy of National Academy of Sciences

RESOURCES