PMID- 10212142
OWN - NLM
STAT- MEDLINE
DCOM- 19990813
LR  - 20171116
IS  - 0021-9533 (Print)
IS  - 0021-9533 (Linking)
VI  - 112 ( Pt 10)
DP  - 1999 May
TI  - The Sec61 complex is located in both the ER and the ER-Golgi intermediate
      compartment.
PG  - 1477-86
AB  - 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.
FAU - Greenfield, J J
AU  - Greenfield JJ
AD  - School of Biological Sciences, University of Manchester, Oxford Road, Manchester 
      M13 9PT, UK.
FAU - High, S
AU  - High S
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - England
TA  - J Cell Sci
JT  - Journal of cell science
JID - 0052457
RN  - 0 (Luminescent Proteins)
RN  - 0 (Membrane Proteins)
RN  - 0 (Protein Synthesis Inhibitors)
RN  - 0 (SEC Translocation Channels)
RN  - 147336-22-9 (Green Fluorescent Proteins)
RN  - 20350-15-6 (Brefeldin A)
SB  - IM
MH  - Animals
MH  - Brefeldin A/pharmacology
MH  - COS Cells
MH  - Endoplasmic Reticulum/*metabolism
MH  - Golgi Apparatus/*metabolism
MH  - Green Fluorescent Proteins
MH  - Luminescent Proteins/metabolism
MH  - Membrane Proteins/analysis/*metabolism
MH  - Microscopy, Fluorescence
MH  - Protein Synthesis Inhibitors/pharmacology
MH  - SEC Translocation Channels
EDAT- 1999/04/23 00:00
MHDA- 1999/04/23 00:01
CRDT- 1999/04/23 00:00
PHST- 1999/04/23 00:00 [pubmed]
PHST- 1999/04/23 00:01 [medline]
PHST- 1999/04/23 00:00 [entrez]
PST - ppublish
SO  - J Cell Sci. 1999 May;112 ( Pt 10):1477-86.