Journal of Cell Science, Vol 112, Issue 10 1477-1486, Copyright © 1999 by Company of Biologists

JOURNAL ARTICLES

The Sec61 complex is located in both the ER and the ER-Golgi intermediate compartment

JJ Greenfield and S High
School of Biological Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK.

The heteromeric Sec61 complex is composed of (alpha), beta and (gamma) subunits and forms the core of the mammalian ER translocon. Oligomers of the Sec61 complex form a transmembrane channel where proteins are translocated across and integrated into the ER membrane. We have studied the subcellular localisation of the Sec61 complex using both wild-type COS1 cells and cells transfected with GFP-tagged Sec61(alpha). By double labelling immunofluorescence microscopy the GFP-tagged Sec61(alpha) was found in both the ER and the ER-Golgi intermediate compartment (ERGIC) but not in the trans-Golgi network. Immunofluorescence studies of endogenous Sec61beta and Sec61(gamma) showed that these proteins are also located in both the ER and the ERGIC. Using the alternative strategy of subcellular fractionation, we have shown that wild-type Sec61(alpha), beta and (gamma), and GFP-tagged Sec61(alpha), are all present in both the ER and the ERGIC/Golgi fractions of the gradient. The presence of the Sec61 subunits in a post-ER compartment suggests that these proteins can escape the ER and be recycled back, despite the fact that none of them contain any known membrane protein retrieval signals such as cytosolic di-lysine or di-arginine motifs. We also found that another translocon component, the glycoprotein TRAM, was present in post-ER compartments as demonstrated by subcellular fractionation. Our data indicate that the core components of the mammalian ER translocon are not permanently resident in the ER, but rather that they are maintained in the ER by a specific retrieval mechanism.

This article has been cited by other articles:

				L. Bengtsson and H. Otto LUMA interacts with emerin and influences its distribution at the inner nuclear membrane J. Cell Sci., February 15, 2008; 121(4): 536 - 548. [Abstract] [Full Text] [PDF]

				M. Garstka, B. Borchert, M. Al-Balushi, P. Praveen, N. Kuhl, I. Majoul, R. Duden, and S. Springer Peptide-receptive Major Histocompatibility Complex Class I Molecules Cycle between Endoplasmic Reticulum and cis-Golgi in Wild-type Lymphocytes J. Biol. Chem., October 19, 2007; 282(42): 30680 - 30690. [Abstract] [Full Text] [PDF]

				J. Butler, A. G. Lee, D. I. Wilson, C. Spalluto, N. A. Hanley, and J. M. East Phospholamban and sarcolipin are maintained in the endoplasmic reticulum by retrieval from the ER-Golgi intermediate compartment Cardiovasc Res, April 1, 2007; 74(1): 114 - 123. [Abstract] [Full Text] [PDF]

				H.-J. Liao and G. Carpenter Role of the Sec61 Translocon in EGF Receptor Trafficking to the Nucleus and Gene Expression Mol. Biol. Cell, March 1, 2007; 18(3): 1064 - 1072. [Abstract] [Full Text] [PDF]

				Y.-K. Bae, H. Qin, K. M. Knobel, J. Hu, J. L. Rosenbaum, and M. M. Barr General and cell-type specific mechanisms target TRPP2/PKD-2 to cilia Development, October 1, 2006; 133(19): 3859 - 3870. [Abstract] [Full Text] [PDF]

				J.-O. De Craene, J. Coleman, P. Estrada de Martin, M. Pypaert, S. Anderson, J. R. Yates III, S. Ferro-Novick, and P. Novick Rtn1p Is Involved in Structuring the Cortical Endoplasmic Reticulum Mol. Biol. Cell, July 1, 2006; 17(7): 3009 - 3020. [Abstract] [Full Text] [PDF]

				L. Song, S. R. DePalma, M. Kharlap, A. G. Zenovich, A. Cirino, R. Mitchell, B. McDonough, B. J. Maron, C. E. Seidman, J.G. Seidman, et al. Novel Locus for an Inherited Cardiomyopathy Maps to Chromosome 7 Circulation, May 9, 2006; 113(18): 2186 - 2192. [Abstract] [Full Text] [PDF]

				L. Shan, M. Yu, H. A.J. Schut, and E. G. Snyderwine Susceptibility of Rats to Mammary Gland Carcinogenesis by the Food-Derived Carcinogen 2-Amino-1-Methyl-6-Phenylimidazo[4,5-b]Pyridine (PhIP) Varies with Age and Is Associated with the Induction of Differential Gene Expression Am. J. Pathol., July 1, 2004; 165(1): 191 - 202. [Abstract] [Full Text] [PDF]

				Y. Elkabetz, A. Kerem, L. Tencer, D. Winitz, R. R. Kopito, and S. Bar-Nun Immunoglobulin Light Chains Dictate Vesicular Transport-dependent and -independent Routes for IgM Degradation by the Ubiquitin-Proteasome Pathway J. Biol. Chem., May 23, 2003; 278(21): 18922 - 18929. [Abstract] [Full Text] [PDF]

				M.-A. Robin, H. K. Anandatheerthavarada, G. Biswas, N. B. V. Sepuri, D. M. Gordon, D. Pain, and N. G. Avadhani Bimodal Targeting of Microsomal CYP2E1 to Mitochondria through Activation of an N-terminal Chimeric Signal by cAMP-mediated Phosphorylation J. Biol. Chem., October 18, 2002; 277(43): 40583 - 40593. [Abstract] [Full Text] [PDF]

				J. Singh, L. Young, D. J. Handelsman, and Q. Dong Prostate Epithelial Expression of a Novel Androgen Target Gene J Androl, September 1, 2002; 23(5): 652 - 660. [Abstract] [Full Text] [PDF]

				A. V. Nikonov, E. Snapp, J. Lippincott-Schwartz, and G. Kreibich Active translocon complexes labeled with GFP-Dad1 diffuse slowly as large polysome arrays in the endoplasmic reticulum J. Cell Biol., August 5, 2002; 158(3): 497 - 506. [Abstract] [Full Text] [PDF]

				A. L. O. Facanha, H. Appelgren, M. Tabish, L. Okorokov, and K. Ekwall The endoplasmic reticulum cation P-type ATPase Cta4p is required for control of cell shape and microtubule dynamics J. Cell Biol., June 10, 2002; 157(6): 1029 - 1040. [Abstract] [Full Text] [PDF]

				I. Nilsson, H. Ohvo-Rekila, J. P. Slotte, A. E. Johnson, and G. von Heijne Inhibition of Protein Translocation across the Endoplasmic Reticulum Membrane by Sterols J. Biol. Chem., November 2, 2001; 276(45): 41748 - 41754. [Abstract] [Full Text] [PDF]

				S. Kamhi-Nesher, M. Shenkman, S. Tolchinsky, S. V. Fromm, R. Ehrlich, and G. Z. Lederkremer A Novel Quality Control Compartment Derived from the Endoplasmic Reticulum Mol. Biol. Cell, June 1, 2001; 12(6): 1711 - 1723. [Abstract] [Full Text] [PDF]

				C. Zuber, M. J. Spiro, B. Guhl, R. G. Spiro, and J. Roth Golgi Apparatus Immunolocalization of Endomannosidase Suggests Post-Endoplasmic Reticulum Glucose Trimming: Implications for Quality Control Mol. Biol. Cell, December 1, 2000; 11(12): 4227 - 4240. [Abstract] [Full Text]

				W. T. Loging, A. Lal, I-M. Siu, T. L. Loney, C. J. Wikstrand, M. A. Marra, C. Prange, D. D. Bigner, R. L. Strausberg, and G. J. Riggins Identifying Potential Tumor Markers and Antigens by Database Mining and Rapid Expression Screening Genome Res., September 1, 2000; 10(9): 1393 - 1402. [Abstract] [Full Text]

				H. Hauri, F Kappeler, H Andersson, and C Appenzeller ERGIC-53 and traffic in the secretory pathway J. Cell Sci., January 2, 2000; 113(4): 587 - 596. [Abstract] [PDF]