The fully linked HTML version of this article has now been published.
JCS ePress
online publication date 19 Apr 2005
doi: 10.1242/jcs.02315
Research Article
Secretory carrier membrane proteins interact and regulate trafficking of the organellar (Na+,K+)/H+ exchanger NHE7
Paulo J.C. Lin,
Warren P. Williams,
Yvonne Luu,
Robert S. Molday,
John Orlowski,
and
Masayuki Numata*
* Author for correspondence (e-mail: mnumata{at}interchange.ubc.ca)
The mammalian (Na+,K+)/H+ exchanger NHE7 resides chiefly in the trans-Golgi network (TGN) and post-Golgi vesicles where it is thought to contribute to organellar pH homeostasis. However, the mechanisms that underlie the targeting and regulation of NHE7 are unknown. To gain insight into these processes, yeast two-hybrid methodology was used to screen a human brain cDNA library for proteins that interact with the cytoplasmic C-terminus of NHE7. One binding partner we identified was SCAMP2, a member of the secretory carrier membrane protein (SCAMP) gene family. Direct association of these two proteins was further supported by co-immunolocalization and co-immunoprecipitation analyses using transfected cells, by their co-sedimentation in membrane fractions resolved on sucrose density gradients, and by in vitro protein binding assays. Other members of the SCAMP family, such as SCAMP1 and SCAMP5, also associated with NHE7. The majority of the NHE7-SCAMP complexes accumulated at the TGN, but a minor fraction also resided in recycling vesicles. Biochemical analyses indicated that the C-terminal cytoplasmic tail of NHE7 bound preferentially to a highly conserved cytoplasmic loop between the second and the third transmembrane segments (TM2-TM3 loop) of SCAMP2. A deletion mutant of SCAMP2 lacking this region (SCAMP2/
184-208) bound weakly to NHE7, but caused a significant fraction of NHE7 and wild-type SCAMP2 to redistribute to a pool of scattered recycling vesicles without noticeably affecting the location of other resident TGN (syntaxin 6) or Golgi cisternae (GM130) proteins. Conversely, a GFP-tagged TM2-TM3 construct of SCAMP2 interacted with NHE7, but also led to the redistribution of NHE7 to dispersed vesicular structures. We propose a model wherein SCAMPs participate in the shuttling of NHE7 between recycling vesicles and the TGN.

CiteULike
Complore
Connotea
Del.icio.us
Digg
Reddit
Technorati
Twitter What's this?
This article has been cited by other articles:

|
 |

|
 |
 
G. H. Diering, J. Church, and M. Numata
Secretory Carrier Membrane Protein 2 Regulates Cell-surface Targeting of Brain-enriched Na+/H+ Exchanger NHE5
J. Biol. Chem.,
May 15, 2009;
284(20):
13892 - 13903.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
K. Toyooka, Y. Goto, S. Asatsuma, M. Koizumi, T. Mitsui, and K. Matsuoka
A Mobile Secretory Vesicle Cluster Involved in Mass Transport from the Golgi to the Plant Cell Exterior
PLANT CELL,
April 1, 2009;
21(4):
1212 - 1229.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
Q. L. Aoh, A. M. Castle, C. H. Hubbard, O. Katsumata, and J. D. Castle
SCAMP3 Negatively Regulates Epidermal Growth Factor Receptor Degradation and Promotes Receptor Recycling
Mol. Biol. Cell,
March 15, 2009;
20(6):
1816 - 1832.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
C. Han, T. Chen, M. Yang, N. Li, H. Liu, and X. Cao
Human SCAMP5, a Novel Secretory Carrier Membrane Protein, Facilitates Calcium-Triggered Cytokine Secretion by Interaction with SNARE Machinery
J. Immunol.,
March 1, 2009;
182(5):
2986 - 2996.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
H. Liao, J. Zhang, S. Shestopal, G. Szabo, A. Castle, and D. Castle
Nonredundant function of secretory carrier membrane protein isoforms in dense core vesicle exocytosis
Am J Physiol Cell Physiol,
March 1, 2008;
294(3):
C797 - C809.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
M. Nowik, M. R. Lecca, A. Velic, H. Rehrauer, A. W. Brandli, and C. A. Wagner
Genome-wide gene expression profiling reveals renal genes regulated during metabolic acidosis
Physiol Genomics,
February 19, 2008;
32(3):
322 - 334.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
R. Ohgaki, N. Fukura, M. Matsushita, K. Mitsui, and H. Kanazawa
Cell Surface Levels of Organellar Na+/H+ Exchanger Isoform 6 Are Regulated by Interaction with RACK1
J. Biol. Chem.,
February 15, 2008;
283(7):
4417 - 4429.
[Abstract]
[Full Text]
[PDF]
|
 |
|
© The Company of Biologists Ltd 2005