Identification of a novel integral plasma membrane protein induced during adipocyte differentiation

2001 ◽  
Vol 359 (2) ◽  
pp. 393-402 ◽  
Author(s):  
Tatjana ALBREKTSEN ◽  
Henrijette E. RICHTER ◽  
Jes T. CLAUSEN ◽  
Jan FLECKNER
Keyword(s):  
Amino Acids ◽  
Plasma Membrane ◽  
Membrane Protein ◽  
Adipocyte Differentiation ◽  
Polyclonal Antibodies ◽  
Glycosylation Site ◽  
Surface Proteins ◽  
Plasma Membrane Protein ◽  
Differential Display Analysis ◽  
Membrane Bound

Adipocyte differentiation is co-ordinately regulated by several transcription factors and is accompanied by changes in the expression of a variety of genes. Using mRNA differential display analysis, we have isolated a novel mRNA, DD16, specifically induced during the course of adipocyte differentiation. DD16 mRNAs are present in several tissues, but among the tissues tested, a remarkably higher level of expression was found in white adipose tissue. The DD16 cDNA encoded a polypeptide of 415 amino acids containing a single N-glycosylation site and an N-terminal hydrophobic stretch of 19 amino acids forming a transmembrane segment, indicating that DD16 is a glycosylated membrane-bound protein. Polyclonal antibodies raised against the DD16 peptide detected immunoreactive DD16 in membrane fractions, notably the plasma membrane. Association of DD16 with the plasma membrane was further confirmed by biotinylation studies of cell surface proteins, suggesting that DD16 is an integral plasma membrane protein. Therefore we propose to give DD16 the name APMAP (Adipocyte Plasma Membrane-Associated Protein). Although the biological function of this polypeptide is presently unknown, our data suggest that APMAP may function as a novel protein involved in the cross-talk of mature adipocytes with the environment.

scholarly journals Identification of a novel integral plasma membrane protein induced during adipocyte differentiation

2001 ◽  
Vol 359 (2) ◽  
pp. 393 ◽  
Author(s):  
Tatjana ALBREKTSEN ◽  
Henrijette E. RICHTER ◽  
Jes T. CLAUSEN ◽  
Jan FLECKNER
Keyword(s):  
Plasma Membrane ◽  
Membrane Protein ◽  
Adipocyte Differentiation ◽  
Plasma Membrane Protein

scholarly journals A 39-kD plasma membrane protein (IP39) is an anchor for the unusual membrane skeleton of Euglena gracilis.

1990 ◽  
Vol 110 (4) ◽  
pp. 1077-1088 ◽  
Author(s):  
T K Rosiere ◽  
J A Marrs ◽  
G B Bouck
Keyword(s):  
Plasma Membrane ◽  
Membrane Protein ◽  
Cell Surface ◽  
Euglena Gracilis ◽  
Plasma Membranes ◽  
Membrane Skeleton ◽  
Surface Proteins ◽  
Plasma Membrane Protein ◽  
Octyl Glucoside ◽  
Skeletal Protein

The major integral plasma membrane protein (IP39) of Euglena gracilis was radiolabeled, peptide mapped, and dissected with proteases to identify cytoplasmic domains that bind and anchor proteins of the cell surface. When plasma membranes were radioiodinated and extracted with octyl glucoside, 98% of the extracted label was found in IP39 or the 68- and 110-kD oligomers of IP39. The octyl glucoside extracts were incubated with unlabeled cell surface proteins immobilized on nitrocellulose (overlays). Radiolabel from the membrane extract bound one (80 kD) of the two (80 and 86 kD) major membrane skeletal protein bands. Resolubilization of the bound label yielded a radiolabeled polypeptide identical in Mr to IP39. Intact plasma membranes were also digested with papain before or after radioiodination, thereby producing a cytoplasmically truncated IP39. The octyl glucoside extract of truncated IP39 no longer bound to the 80-kD membrane skeletal protein in the nitrocellulose overlays. EM of intact or trypsin digested plasma membranes incubated with membrane skeletal proteins under stringent conditions similar to those used in the nitrocellulose overlays revealed a partially reformed membrane skeletal layer. Little evidence of a membrane skeletal layer was found, however, when plasma membranes were predigested with papain before reassociation. A candidate 80-kD binding domain of IP39 has been tentatively identified as a peptide fragment that was present after trypsin digestion of plasma membranes, but was absent after papain digestion in two-dimensional peptide maps of IP39. Together, these data suggest that the unique peripheral membrane skeleton of Euglena binds to the plasma membrane through noncovalent interactions between the major 80-kD membrane skeletal protein and a small, papain sensitive cytoplasmic domain of IP39. Other (62, 51, and 25 kD) quantitatively minor peripheral proteins also interact with IP39 on the nitrocellulose overlays, and the possible significance of this binding is discussed.

The transcytotic pathway of an apical plasma membrane protein (B10) in hepatocytes is similar to that of IgA and occurs via a tubular pericentriolar compartment

1996 ◽  
Vol 109 (6) ◽  
pp. 1215-1227 ◽  
Author(s):  
I. Hemery ◽  
A.M. Durand-Schneider ◽  
G. Feldmann ◽  
J.P. Vaerman ◽  
M. Maurice
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Apical Membrane ◽  
Rat Hepatocytes ◽  
Apical Plasma Membrane ◽  
Apical Surface ◽  
Plasma Membrane Protein ◽  
Microtubule Disruption

In hepatocytes, newly synthesized apical plasma membrane proteins are first delivered to the basolateral surface and are supposed to reach the apical surface by transcytosis. The transcytotic pathway of apical membrane proteins and its relationship with other endosomal pathways has not been demonstrated morphologically. We compared the intracellular route of an apical plasma membrane protein, B10, with that of polymeric IgA (pIgA), which is transcytosed, transferrin (Tf) which is recycled, and asialoorosomucoid (ASOR) which is delivered to lysosomes. Ligands and anti-B10 monoclonal IgG were linked to fluorochromes or with peroxidase. The fate of each ligand was followed by confocal and electron microscopy in polarized primary monolayers of rat hepatocytes. When fluorescent anti-B10 IgG and fluorescent pIgA were simultaneously endocytosed for 15–30 minutes, they both uniformly labelled a juxtanuclear compartment. By 30–60 minutes, they reached the bile canaliculi. Tf and ASOR were also routed to the juxtanuclear area, but their fluorescence patterns were more punctate. Microtubule disruption prevented all ligands from reaching the juxtanuclear area. This area corresponded, at least partially, to the localization of the mannose 6-phosphate receptor, an endosomal marker. By electron microscopy, the juxtanuclear compartment was made up of anastomosing tubules connected to vacuoles, and was organized around the centrioles. B10 and pIgA were mainly found in the tubules, whereas ASOR was segregated inside the vacuolar elements and Tf within thinner, recycling tubules. In conclusion, transcytosis of the apical membrane protein B10 occurs inside tubules similar to those carrying pIgA, and involves passage via the pericentriolar area. In the pericentriolar area, the transcytotic tubules appear to maintain connections with other endosomal elements where sorting between recycled and degraded ligands occurs.

scholarly journals Sendai-viral HN and F glycoproteins as probes of plasma-membrane protein catabolism in HTC cells. Studies with fusogenic reconstituted Sendai-viral envelopes

1987 ◽  
Vol 241 (3) ◽  
pp. 801-807 ◽  
Author(s):  
R T Earl ◽  
E E Billett ◽  
I M Hunneyball ◽  
R J Mayer
Keyword(s):  
Plasma Membrane ◽  
Membrane Protein ◽  
Plasma Membranes ◽  
Viral Proteins ◽  
Plasma Membrane Protein ◽  
Lysosomal Degradation ◽  
Cell Plasma ◽  
Degradation Rates ◽  
Htc Cells ◽  
Viral Envelopes

Reconstituted Sendai-viral envelopes (RSVE) were produced by the method of Vainstein, Hershkovitz, Israel & Loyter [(1984) Biochim. Biophys. Acta 773, 181-188]. RSVE are fusogenic unilamellar vesicles containing two transmembrane glycoproteins: the HN (haemagglutinin-neuraminidase) protein and the F (fusion) factor. The fate of the viral proteins after fusion-mediated transplantation of RSVE into hepatoma (HTC) cell plasma membranes was studied to probe plasma-membrane protein degradation. Both protein species are degraded at similar, relatively slow, rates (t1/2 = 67 h) in HTC cells fused with RSVE in suspension. Even slower degradation rates for HN and F proteins (t1/2 = 93 h) were measured when RSVE were fused with HTC cells in monolayer. Lysosomal degradation of the transplanted viral proteins is strongly implicated by the finding that degradation of HN and F proteins is sensitive to inhibition by 10 mM-NH4Cl (81%) and by 50 micrograms of leupeptin/ml (70%).

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