scholarly journals Secretory carrier membrane proteins interact and regulate trafficking of the organellar (Na+,K+)/H+ exchanger NHE7

2005 ◽  
Vol 118 (9) ◽  
pp. 1885-1897 ◽  
Author(s):  
P. J. C. Lin
Keyword(s):  
Membrane Proteins ◽  
Secretory Carrier Membrane Proteins

scholarly journals Tyrosine Phosphorylation of Selected Secretory Carrier Membrane Proteins, SCAMP1 and SCAMP3, and Association with the EGF Receptor

1998 ◽  
Vol 9 (7) ◽  
pp. 1661-1674 ◽  
Author(s):  
Theodore T. Wu ◽  
J. David Castle
Keyword(s):  
Membrane Proteins ◽  
Egf Receptor ◽  
Tyrosine Phosphatase ◽  
Chinese Hamster ◽  
Tyrosine Residue ◽  
Cell Interior ◽  
Murine Fibroblasts ◽  
Secretory Carrier Membrane Proteins

Secretory carrier membrane proteins (SCAMPs) are ubiquitously expressed proteins of post-Golgi vesicles. In the presence of the tyrosine phosphatase inhibitor vanadate, or after overexpression in Chinese hamster ovary (CHO) cells, SCAMP1 and SCAMP3 are phosphorylated selectively on tyrosine residue(s). Phosphorylation is reversible after vanadate washout in situ or when isolated SCAMP3 is incubated with the recombinant tyrosine phosphatase PTP1B. Vanadate also causes the partial accumulation of SCAMP3, but not SCAMP1, in “patches” at or near the cell surface. A search for SCAMP kinase activities has shown that SCAMPs 1 and 3, but not SCAMP2, are tyrosine phosphorylated in EGF-stimulated murine fibroblasts overexpressing the EGF receptor (EGFR). EGF catalyzes the progressive phosphorylation of the SCAMPs up to 1 h poststimulation and may enhance colocalization of the EGFR and SCAMP3 within the cell interior. EGF also induces SCAMP–EGFR association, as detected by coimmunoprecipitation, and phosphorylation of SCAMP3 is stimulated by the EGFR in vitro. These results suggest that phosphorylation of SCAMPs, either directly or indirectly, may be functionally linked to the internalization/down-regulation of the EGFR.

Three mammalian SCAMPs (secretory carrier membrane proteins) are highly related products of distinct genes having similar subcellular distributions

1997 ◽  
Vol 110 (17) ◽  
pp. 2099-2107 ◽  
Author(s):  
D.R. Singleton ◽  
T.T. Wu ◽  
J.D. Castle
Keyword(s):  
Membrane Proteins ◽  
Mammalian Species ◽  
In Vitro Transcription ◽  
Complete Analysis ◽  
Mammalian Tissues ◽  
Double Label ◽  
Secretory Carrier Membrane Proteins ◽  
Expressed Sequence ◽  
Cognate Mrnas

The primary structures of three human forms of secretory carrier membrane proteins (SCAMPs) have been deduced from full-length clones isolated from a HeLa cell cDNA library and confirmed by a combination of comparison to expressed sequence tags, microsequencing of purified protein, and in vitro transcription and translation. The structures indicated that SCAMPs are highly related products of distinct genes, and that the sequence identity of an individual SCAMP between different mammalian species is almost complete. Analysis of the distribution of SCAMPs among different mammalian tissues and cells indicates parallel expression of polypeptides and cognate mRNAs, and indicates that the three SCAMPs are usually but not always expressed together. The apparent M(r)s of two SCAMPs (1 and 2) do not vary appreciably among species, while that of the third (SCAMP3) is approximately 2 kDa larger in rodent cells than in humans. Examination of the codistribution of the three forms within individual cells using double label immunofluorescence indicates extensive colocalization of SCAMP2 and SCAMP3 with endogenous SCAMP1, however, subcellular regions enriched for a particular SCAMP are readily visible. These findings suggest that the SCAMPs may largely function at the same sites during vesicular transport rather than in separate post-Golgi recycling pathways.

scholarly journals Two Rab proteins, vesicle-associated membrane protein 2 (VAMP-2) and secretory carrier membrane proteins (SCAMPs), are present on immunoisolated parietal cell tubulovesicles

1997 ◽  
Vol 325 (2) ◽  
pp. 559-564 ◽  
Author(s):  
Benjamin C. CALHOUN ◽  
James R. GOLDENRING
Keyword(s):  
Monoclonal Antibodies ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Parietal Cell ◽  
Vesicle Fusion ◽  
Parietal Cells ◽  
Rab Proteins ◽  
Α Subunit ◽  
Gastric Parietal Cell ◽  
Secretory Carrier Membrane Proteins

The tubulovesicles of gastric parietal cells sequester H+/K+-ATPase molecules within resting parietal cells. Stimulation of parietal cell secretion elicits delivery of intracellular H+/K+-ATPase to the apically oriented secretory canaliculus. Previous investigations have suggested that this process requires the regulated fusion of intracellular tubulovesicles with the canalicular target membrane. We have sought to investigate the presence of critical putative regulators of vesicle fusion on immunoisolated gastric parietal cell tubulovesicles. Highly purified tubulovesicles were prepared by gradient fractionation and immunoisolation on magnetic beads coated with monoclonal antibodies against the α subunit of H+/K+-ATPase. Western blot analysis revealed the presence of Rab11, Rab25, vesicle-associated membrane protein 2 (VAMP-2) and secretory carrier membrane proteins (SCAMPs) on immunoisolated vesicles. The same cohort of proteins was recovered on vesicles immunoisolated with monoclonal antibodies against SCAMPs and VAMP-2. In contrast, whereas immunoreactivities for syntaxin 1A/1B and synaptosome-associated protein (SNAP-25) were present in gradient-isolated vesicles, none of the immunoreactivity was associated with immunoisolated vesicles. The observation of VAMP-2 and two Rab proteins on immunoisolated H+/K+-ATPase-containing tubulovesicles supports the role for tubulovesicles in a regulated vesicle fusion process. In addition, the presence of SCAMPs along with Rab11 and Rab25 implicates the tubulovesicles as a critical apical recycling vesicle population.

Secretory carrier membrane proteins

PROTOPLASMA ◽  
2011 ◽  
Vol 249 (2) ◽  
pp. 269-283 ◽  
Author(s):  
Angus Ho Yin Law ◽  
Cheung-Ming Chow ◽  
Liwen Jiang
Keyword(s):  
Membrane Proteins ◽  
Secretory Carrier Membrane Proteins

Evidence for colocalization and interaction between 37 and 39 kDa isoforms of secretory carrier membrane proteins (SCAMPs)

1997 ◽  
Vol 110 (13) ◽  
pp. 1533-1541 ◽  
Author(s):  
T.T. Wu ◽  
J.D. Castle
Keyword(s):  
Membrane Proteins ◽  
Acinar Cells ◽  
Chemical Crosslinking ◽  
Vesicle Membrane ◽  
Parotid Acinar Cells ◽  
Single Protein ◽  
Transport Vesicle ◽  
Potential Formation ◽  
Secretory Carrier Membrane Proteins

Secretory carrier membrane proteins (SCAMPs) are proteins of post-Golgi recycling carriers, including regulated secretory organelles. The two major size variants, SCAMP1 (37 kDa) and SCAMP2 (39 kDa), extensively colocalize in membranes of fibroblasts and parotid acinar cells based on immunocytochemistry and velocity centrifugation, although the relative amounts of each variant may differ in selected organelles. SCAMP1, and to a lesser extent, SCAMP2, are substrates for chemical crosslinking in situ, and the recognizable crosslinking products of SCAMP1 suggest potential formation of homomultimers. SCAMP1 and SCAMP2 can be co-immunoprecipitated following detergent solubilization, using antibodies that specifically react with only one of the variants. Both the localization and interactions of SCAMPs are reiterated using transfected SCAMP1 that is epitope tagged (myc) at either the NH2 or COOH terminus and an anti-myc antibody. Like other transport vesicle membrane proteins, SCAMPs form complexes that apparently include homomultimers. Furthermore, these studies suggest that both SCAMP1 and SCAMP2 may function together in a single protein complex.

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