Abstract
We describe a method that can be used to produce equimolar amounts of two or more specific proteins in a cell. In this approach, termed the ubiquitin/protein/reference (UPR) technique, a reference protein and a protein of interest are synthesized as a polyprotein separated by a ubiquitin moiety. This tripartite fusion is cleaved, cotranslationally or nearly so, by ubiquitin-specific processing proteases after the last residue of ubiquitin, producing equimolar amounts of the protein of interest and the reference protein bearing a C-terminal ubiquitin moiety. In applications such as pulse-chase analysis, the UPR technique can compensate for the scatter of immunoprecipitation yields, sample volumes, and other sources of sample-to-sample variation. In particular, this method allows a direct comparison of proteins' metabolic stabilities from the pulse data alone. We used UPR to examine the N-end rule (a relation between the in vivo half-life of a protein and the identity of its N-terminal residue) in L cells, a mouse cell line. The increased accuracy afforded by the UPR technique underscores insufficiency of the current "half-life" terminology, because in vivo degradation of many proteins deviates from first-order kinetics. We consider this problem and discuss other applications of UPR.
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- Alagramam K., Naider F., Becker J. M. A recognition component of the ubiquitin system is required for peptide transport in Saccharomyces cerevisiae. Mol Microbiol. 1995 Jan;15(2):225–234. doi: 10.1111/j.1365-2958.1995.tb02237.x. [DOI] [PubMed] [Google Scholar]
- Arfin S. M., Bradshaw R. A. Cotranslational processing and protein turnover in eukaryotic cells. Biochemistry. 1988 Oct 18;27(21):7979–7984. doi: 10.1021/bi00421a001. [DOI] [PubMed] [Google Scholar]
- Bachmair A., Finley D., Varshavsky A. In vivo half-life of a protein is a function of its amino-terminal residue. Science. 1986 Oct 10;234(4773):179–186. doi: 10.1126/science.3018930. [DOI] [PubMed] [Google Scholar]
- Bachmair A., Varshavsky A. The degradation signal in a short-lived protein. Cell. 1989 Mar 24;56(6):1019–1032. doi: 10.1016/0092-8674(89)90635-1. [DOI] [PubMed] [Google Scholar]
- Baker R. T., Tobias J. W., Varshavsky A. Ubiquitin-specific proteases of Saccharomyces cerevisiae. Cloning of UBP2 and UBP3, and functional analysis of the UBP gene family. J Biol Chem. 1992 Nov 15;267(32):23364–23375. [PubMed] [Google Scholar]
- Baker R. T., Varshavsky A. Inhibition of the N-end rule pathway in living cells. Proc Natl Acad Sci U S A. 1991 Feb 15;88(4):1090–1094. doi: 10.1073/pnas.88.4.1090. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Baker R. T., Varshavsky A. Yeast N-terminal amidase. A new enzyme and component of the N-end rule pathway. J Biol Chem. 1995 May 19;270(20):12065–12074. doi: 10.1074/jbc.270.20.12065. [DOI] [PubMed] [Google Scholar]
- Finley D., Bartel B., Varshavsky A. The tails of ubiquitin precursors are ribosomal proteins whose fusion to ubiquitin facilitates ribosome biogenesis. Nature. 1989 Mar 30;338(6214):394–401. doi: 10.1038/338394a0. [DOI] [PubMed] [Google Scholar]
- Gonda D. K., Bachmair A., Wünning I., Tobias J. W., Lane W. S., Varshavsky A. Universality and structure of the N-end rule. J Biol Chem. 1989 Oct 5;264(28):16700–16712. [PubMed] [Google Scholar]
- Heim R., Cubitt A. B., Tsien R. Y. Improved green fluorescence. Nature. 1995 Feb 23;373(6516):663–664. doi: 10.1038/373663b0. [DOI] [PubMed] [Google Scholar]
- Hershko A., Ciechanover A. The ubiquitin system for protein degradation. Annu Rev Biochem. 1992;61:761–807. doi: 10.1146/annurev.bi.61.070192.003553. [DOI] [PubMed] [Google Scholar]
- Hochstrasser M., Varshavsky A. In vivo degradation of a transcriptional regulator: the yeast alpha 2 repressor. Cell. 1990 May 18;61(4):697–708. doi: 10.1016/0092-8674(90)90481-s. [DOI] [PubMed] [Google Scholar]
- Jentsch S., Schlenker S. Selective protein degradation: a journey's end within the proteasome. Cell. 1995 Sep 22;82(6):881–884. doi: 10.1016/0092-8674(95)90021-7. [DOI] [PubMed] [Google Scholar]
- Johnsson N., Varshavsky A. Ubiquitin-assisted dissection of protein transport across membranes. EMBO J. 1994 Jun 1;13(11):2686–2698. doi: 10.1002/j.1460-2075.1994.tb06559.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lemm J. A., Rümenapf T., Strauss E. G., Strauss J. H., Rice C. M. Polypeptide requirements for assembly of functional Sindbis virus replication complexes: a model for the temporal regulation of minus- and plus-strand RNA synthesis. EMBO J. 1994 Jun 15;13(12):2925–2934. doi: 10.1002/j.1460-2075.1994.tb06587.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Madura K., Varshavsky A. Degradation of G alpha by the N-end rule pathway. Science. 1994 Sep 2;265(5177):1454–1458. doi: 10.1126/science.8073290. [DOI] [PubMed] [Google Scholar]
- Papa F. R., Hochstrasser M. The yeast DOA4 gene encodes a deubiquitinating enzyme related to a product of the human tre-2 oncogene. Nature. 1993 Nov 25;366(6453):313–319. doi: 10.1038/366313a0. [DOI] [PubMed] [Google Scholar]
- Ross J. mRNA stability in mammalian cells. Microbiol Rev. 1995 Sep;59(3):423–450. doi: 10.1128/mr.59.3.423-450.1995. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ryan M. D., Drew J. Foot-and-mouth disease virus 2A oligopeptide mediated cleavage of an artificial polyprotein. EMBO J. 1994 Feb 15;13(4):928–933. doi: 10.1002/j.1460-2075.1994.tb06337.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Tobias J. W., Shrader T. E., Rocap G., Varshavsky A. The N-end rule in bacteria. Science. 1991 Nov 29;254(5036):1374–1377. doi: 10.1126/science.1962196. [DOI] [PubMed] [Google Scholar]
- Varshavsky A. The N-end rule. Cold Spring Harb Symp Quant Biol. 1995;60:461–478. doi: 10.1101/sqb.1995.060.01.051. [DOI] [PubMed] [Google Scholar]
- de Groot R. J., Rümenapf T., Kuhn R. J., Strauss E. G., Strauss J. H. Sindbis virus RNA polymerase is degraded by the N-end rule pathway. Proc Natl Acad Sci U S A. 1991 Oct 15;88(20):8967–8971. doi: 10.1073/pnas.88.20.8967. [DOI] [PMC free article] [PubMed] [Google Scholar]