The glucose transporter GluT4 and secretory carrier membrane proteins (SCAMPs) colocalize in rat adipocytes and partially segregate during insulin stimulation.

Laurie, S M; Cain, C C; Lienhard, Gustav E.; Castle, J. David

doi:10.1016/s0021-9258(17)46741-x

Cited by 112 publications

(16 citation statements)

References 25 publications

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“…As noted above, GLUT4-enriched vesicles contain a muscleand fat-specific aminopeptidase, gp160 , and they also possess three antigenically related integral membrane proteins of unknown function, called SCAMPs/GTV3 for secretory component-associated membrane protein/glucose transporter vesicle triplet (Brand et al, 1991;Thoidis et al, 1993;Laurie et al, 1993). Fig.…”

Section: Resultsmentioning

confidence: 97%

Identification and Characterization of an Exercise-sensitive Pool of Glucose Transporters in Skeletal Muscle

Coderre¹,

Kandror²,

Vallega

et al. 1995

Journal of Biological Chemistry

174

121

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Augmentation of glucose transport into skeletal muscle by GLUT4 translocation to the plasma and T-tubule membranes can be mediated independently by insulin and by contraction/exercise. Available data suggest that separable pools of intracellular GLUT4 respond to these two stimuli. To identify and characterize these pools, we fractionated skeletal muscle membranes in a discontinuous sucrose density gradient. Fractions of 32 and 36% sucrose exhibited the highest enrichment of GLUT4 and were independently responsive to insulin and exercise, respectively. The combination of the two stimuli depleted both GLUT4 fractions simultaneously. Both vesicle populations contained the gp160 aminopeptidase, whose expression had previously been shown to be specific to muscle and fat and restricted to GLUT4 vesicles in the latter tissue. In muscle, gp160 translocates exactly as does GLUT4 in response to insulin and exercise. The contraction- and insulin-sensitive GLUT4 pools also contained secretory component-associated membrane protein/glucose transporter vesicle triplet but not GLUT1 and caveolin. Immunoadsorption of the two pools followed by silver staining did not reveal any obvious difference in their major protein components. On the other hand, sedimentational analysis in sucrose velocity gradients revealed that the insulin-sensitive GLUT4 vesicles had a larger sedimentation coefficient than the exercise-sensitive vesicles. Thus, the separation of the two intracellular GLUT4 pools should be useful in dissecting what are likely to be different signal transduction pathways that mediate their translocation to the cell surface.

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Section: Resultsmentioning

confidence: 97%

Identification and Characterization of an Exercise-sensitive Pool of Glucose Transporters in Skeletal Muscle

Coderre¹,

Kandror²,

Vallega

et al. 1995

Journal of Biological Chemistry

174

121

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“…Probably the best correlation was observed between the staining of pantophysin and SCAMPs, which are integral membrane proteins of secretory and cell surface recycling vesicles (Fig. 7, d and d'; see references 7,8,38). Furthermore, cellubrevin, a cellular homologue of the synaptic vesicle protein synaptobrevin (47), showed significant colocalization with pantophysin in A431 cells as well (Fig.…”

Section: Pantophysin Colocalization With Cytoplasmic Vesicle Markersmentioning

confidence: 83%

“…For example, isoforms of the vSNARE synaptobrevin have been shown to colocalize with transferrincontaining recycling vesicles in fibroblasts (24, 47), with vesicles in the ER/Golgi region of skeletal muscle (58, 71), with zymogen granules of exocrine cells and dense core vesicles of J3 cells in pancreas (9, 59), with glucose transporter--containing vesicles in adipocytes(10), or water channels in the collecting ducts of kidney(22). Conversely, SCAMPs are not only constituents of secretory and endocytotic vesicles in nonneuroendocrine cells but also of synaptic vesicles(7,8,38). Expression of the individual family members is not mutually exclusive (see for exampleFig.…”

mentioning

confidence: 99%

Pantophysin is a ubiquitously expressed synaptophysin homologue and defines constitutive transport vesicles.

Haass

Kartenbeck

Leube

1996

The Journal of Cell Biology

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Abstract. Certain properties of the highly specialized synaptic transmitter vesicles are shared by constitutively occurring vesicles. We and others have thus identified a cDNA in various nonneuroendocrine cell types of rat and human that is related to synaptophysin, one of the major synaptic vesicle membrane proteins, which we termed pantophysin. Here we characterize the gene structure, mRNA and protein expression, and intracellular distribution of pantophysin. Its mRNA is detected in murine cell types of nonneuroendocrine as well as of neuroendocrine origin. The intron/exon structure of the murine pantophysin gene is identical to that of synaptophysin except for the last intron that is absent in pantophysin. The encoded polypeptide of calculated mol wt 28,926 shares many sequence features with synaptophysin, most notably the four hydrophobic putative transmembrane domains, although the cytoplasmic end domains are completely different. Using antibodies against the unique carboxy terminus pantophysin can be detected by immunofluorescence microscopy in both exocrine and endocrine cells of human pancreas, and in cultured cells, colocalizing with constitutive secretory and endocytotic vesicle markers in nonneuroendocrine cells and with synaptophysin in cDNAtransfected epithelial cells. By immunoelectron microscopy, the majority of pantophysin reactivity is detected at vesicles with a diameter of <100 nm that have a smooth surface and an electron-translucent interior. Using cell fractionation in combination with immunoisolation, these vesicles are enriched in a light fraction and shown to contain the cellular vSNARE cellubrevin and the ubiquitous SCAMPs in epithelial cells and synaptophysin in neuroendocrine or cDNA-transfected nonneuroendocrine cells and neuroendocrine tissues. Pantophysin is therefore a broadly distributed marker of small cytoplasmic transport vesicles independent of their content. TRANSPORT between discontinuous cellular membranes is dependent on the presence of small carrier vesicles. Such vesicles have been identified and characterized in various pathways connecting, e.g., ERand Golgi apparatus, cis-and trans-Golgi cisternae, Golgi apparatus and lysosomes, trans-Golgi network and plasma membrane, or plasma membrane and endosomes (for description of such transport vesicles see references 4, 14, 28, 48, 51-53; for review see references 19, 56, 57). While it has been shown in many instances that the assembly of a defined "coat" is of importance for selective vesicle formation from a donor membrane (for example see references 2, 51, 55, 61, 65, 74), and that a multimolecular fusion complex is involved in vesicle fusion with a particular target membrane (for recent review see references 6, 20, 61, 66), very little is known about basic requirements for vesicle maintenance in the "free" cytoplasmic state. A suitable model system to examine principles determining vesicle morphogenesis is the synaptic, transmittercontaining, small secretory vesicle in neurons. Its major components have been characterized...

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“…8) roughly corresponding to a molecular mass of 160 kD, which is in excellent agreement with the original observation by . We saw no overlap between the sedimentation patterns of detergent-solubilized caveolin and GLUT4, or other known proteins of GLUT4-contalning vesicles such as GTV3/SCAMPs (Thoidis et al, 1993;Laurie et al, 1993) and small GTP-binding proteins (Cormont et al, 1991). When solubilized in detergent, these vesicular components sediment as monomers in the zone corresponding to their predicted molecular mass (data not shown).…”

Section: R E S U L T Smentioning

confidence: 86%

Expression and compartmentalization of caveolin in adipose cells: coordinate regulation with and structural segregation from GLUT4.

Kandror

Stephens

Pilch

1995

The Journal of Cell Biology

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Abstract. Native rat adipocytes and the mouse adipocyte cell line, 3T3-L1, possess transport vesicles of apparently uniform composition and size which translocate the tissue-specific glucose transporter isoform, GLUT4, from an intracellular pool to the cell surface in an insulin-sensitive fashion. Caveolin, the presumed structural protein of caveolae, has also been proposed to function in vesicular transport. Thus, we studied the expression and subcellular distribution of caveolin in adipocytes. We found that rat fat cells express the highest level of caveolin protein of any tissue studied, and caveolin is also expressed at high levels in cardiac muscle, another tissue possessing insulin responsive GLUT4 translocation. Both proteins are absent from 3T3-L1 fibroblasts and undergo a dramatic coordinate increase in expression upon differentiation of these cells into adipocytes. However, unlike GLUT4 in rat adipocytes not exposed to insulin, the majority of cavcolin is present in the plasma membrane. In native rat adipocytes, intracellular GLUT4 and caveolin reside in vesicles practically indistinguishable by their size and buoyant density in sucrose gradients, and both proteins show insulin-dependent translocation to the cell surface. However, by immunoadsorption of GLUT4-containing vesicles with anti-GLUT4 antibody, we show that these vesicles have no detectable caveolin, and therefore, this protein is present in a distinct vesicle population. Thus, caveolin has no direct structural relation to the organization of the intracellular glucose transporting machinery in fat cells.

show abstract

The glucose transporter GluT4 and secretory carrier membrane proteins (SCAMPs) colocalize in rat adipocytes and partially segregate during insulin stimulation.

Cited by 112 publications

References 25 publications

Identification and Characterization of an Exercise-sensitive Pool of Glucose Transporters in Skeletal Muscle

Identification and Characterization of an Exercise-sensitive Pool of Glucose Transporters in Skeletal Muscle

Pantophysin is a ubiquitously expressed synaptophysin homologue and defines constitutive transport vesicles.

Expression and compartmentalization of caveolin in adipose cells: coordinate regulation with and structural segregation from GLUT4.

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