scholarly journals The decrease in the short variant of gsalpha protein is associated with an increase in [3H]CGP12177 binding, [3H]ouabain binding and Na, K-ATPase activity in brown adipose tissue plasma membranes of cold-acclimated hamsters

1999 ◽  
Vol 22 (1) ◽  
pp. 55-64 ◽  
Author(s):  
L Bourova ◽  
J Novotn ◽  
P Svoboda
Keyword(s):  
Adipose Tissue ◽  
Plasma Membrane ◽  
Atpase Activity ◽  
Brown Adipose Tissue ◽  
Binding Sites ◽  
Plasma Membranes ◽  
Immunoblot Analysis ◽  
Ouabain Binding ◽  
Brown Adipose ◽  
Sds Page

Sucrose density gradient purified plasma membranes isolated from brown adipose tissue of cold-acclimated hamsters (4-10 weeks at 0-4 degreesC) were analysed for the content of the short (GsalphaS) and long (GsalphaL) variants of Gsalpha protein (the alpha subunit of the stimulatory G protein) and compared with the membranes isolated from control animals. The relative ratio between the two variants (GsalphaS/GsalphaL) decreased from 0.48 to 0.24 (P<0.01). This result, obtained by electrophoretic resolution of membrane proteins by standard SDS-PAGE and an immunoblot analysis with an antiserum oriented against an internal sequence of Gsalpha, was verified by resolution on urea-containing gels and an antiserum oriented against the C-terminus decapeptide of Gsalpha. Under these conditions, the GsalphaS/GsalphaL ratio was decreased from 0.41 to 0.31 (P<0.05). The total amount of both isoforms (GsalphaS plus GsalphaL) decreased to 83% (P<0.05) or 68% (P<0.01) by standard or urea SDS-PAGE respectively. These data demonstrate that cold-acclimation of hamster brown adipose tissue is associated with preferential decrease in the plasma membrane density of the short variant of the Gsalpha protein.%This decrease was paralleled by an increase in the other plasma membrane constituents, [3H]CGP12177 binding sites, [3H]ouabain binding sites and Na,K-ATPase activity to 147%, 212% and 191% respectively.

scholarly journals Distribution of the integral plasma membrane glycoprotein CE9 (MRC OX-47) among rat tissues and its induction by diverse stimuli of metabolic activation

1995 ◽  
Vol 310 (2) ◽  
pp. 693-698 ◽  
Author(s):  
C L Nehme ◽  
B E Fayos ◽  
J R Bartles
Keyword(s):  
Adipose Tissue ◽  
Plasma Membrane ◽  
Brown Adipose Tissue ◽  
Plasma Membranes ◽  
Metabolic Activation ◽  
Blast Transformation ◽  
Rat Tissues ◽  
Membrane Glycoprotein ◽  
Brown Adipose ◽  
Different Tissues

We have compared the levels of the integral plasma membrane glycoprotein CE9 (MRC OX-47) in different tissues of the rat and have ascertained that the levels of CE9 protein and mRNA in selected tissues and cells exhibit moderate increases in response to diverse stimuli of metabolic activation. When normalized on the basis of total protein, the level of CE9 detected in the different tissues was found to vary over a 50-fold range. In addition, the apparent molecular mass of CE9 was observed to vary from 40 kDa to 68 kDa as a consequence of tissue-specific glycosylation. The highest level of CE9 was detected in brown adipose tissue, where the protein was found to be localized to the plasma membranes of the adipocytes. The metabolic activation of brown adipose tissue that occurs upon exposure of rats to the cold was found to be accompanied by 3.0 +/- 0.4-fold and 1.7 +/- 0.2-fold increases in the levels of CE9 mRNA and protein respectively. An intermediate level of CE9 was detected in the liver, where the protein is known to be expressed within the basolateral domain of the hepatocyte plasma membrane. The metabolic activation of hepatocytes that occurs upon administration of thyroid hormone to euthyroid rats was found to be accompanied by 2.2 +/- 0.3-fold and 1.9 +/- 0.3-fold increases in the levels of CE9 mRNA and protein respectively. A low level of CE9 was detected in the lymphoid organs, such as thymus and spleen. The metabolic activation of isolated rat splenocytes that occurs upon concanavalin A-mediated blast transformation in culture was found to be accompanied by 2.1 +/- 0.2-fold and 1.6 +/- 0.2-fold increases in the levels of CE9 mRNA and protein respectively. On the basis of these and other observations, we suggest that the level, and possibly also the localization, of the integral plasma membrane glycoprotein CE9 may be correlated in a positive fashion with metabolic activity in a diverse array of cell types.

scholarly journals Resolution and identification of Gq/G11alpha and Gialpha/Goalpha proteins in brown adipose tissue: effect of cold acclimation

1999 ◽  
Vol 23 (2) ◽  
pp. 223-229 ◽  
Author(s):  
L Bourova ◽  
J Novotny ◽  
P Svoboda
Keyword(s):  
Adipose Tissue ◽  
Plasma Membrane ◽  
Brown Adipose Tissue ◽  
Cold Acclimation ◽  
Plasma Membranes ◽  
Brown Adipose ◽  
Guanine Nucleotide Binding ◽  
G 11 ◽  
Carboxy Terminal ◽  
Nucleotide Binding Proteins

Levels of guanine nucleotide-binding proteins G(q)alpha and G(11)alpha, which produce receptor regulation of phospholipase C, were measured immunologically in purified plasma membrane fractions of hamster brown adipose tissue (BAT). This was achieved by immunoblotting with antisera (CQ series) that identify these two polypeptides equally, following separation of the plasma membranes using SDS-PAGE in the presence of 6 M urea, i.e. conditions that can resolve G(q)alpha and G(11)alpha. The ratio of levels of G(q)alpha to G(11)alpha was 1:1. A similar approach was used for resolution and identification of G(o)1alpha and G(o)2alpha, the latter representing the prevailing form of G(o)alpha proteins in this tissue. Although clearly recognized in brain microsomes, which were used as positive controls, no detected levels of G(o)*alpha protein were noted. Using specific anti-peptide antibodies directed against the carboxy-terminal decapeptide of G(i)3alpha, this G protein was also found to be expressed in BAT tissue. Cold acclimation resulted in reduction of the plasma membrane levels of all these Galpha proteins.

scholarly journals Characterization of [3H]Dihydroergocryptine Binding Sites in Brown Adipose Tissue. Evidence for the Presence of alpha-Adrenergic Receptors.

1980 ◽  
Vol 34b ◽  
pp. 231-232 ◽  
Author(s):  
Jan Svartengren ◽  
Nina Mohell ◽  
Barbara Cannon ◽  
Kari Daasvatn ◽  
Jan-Erik Berg ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Binding Sites ◽  
Adrenergic Receptors ◽  
Alpha Adrenergic Receptors ◽  
Brown Adipose

Rapid changes in number of GDP binding sites on brown adipose tissue mitochondria

1986 ◽  
Vol 251 (2) ◽  
pp. E192-E195
Author(s):  
A. G. Swick ◽  
R. W. Swick
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Binding Sites ◽  
Uncoupling Protein ◽  
Membrane Integrity ◽  
Binding Activity ◽  
Bat Mitochondria ◽  
Brown Adipose ◽  
Rapid Changes ◽  
Binding To Mitochondria

GDP binding to brown adipose tissue (BAT) mitochondria increased more than twofold in 20 min when rats were moved from 27 to 4 degrees C. When animals housed at 4 degrees C for 2 h were returned to 27 degrees C, GDP binding decreased sharply in 20 min and returned to control levels in 2 h. These results are consistent with a rapid unmasking and remasking of GDP binding sites. GDP binding to mitochondria from warm and acutely cold treated rats was not modified by prior swelling, by freeze-thawing, nor by sonication of the mitochondria before assay. GDP-inhibitable proton conductance, as measured by passive swelling, was unaffected by this brief exposure to cold but more than doubled in rats kept at 4 degrees C for 10 days. We hypothesize that the rate of GDP-inhibitable swelling may be a reflection of uncoupling protein concentration in the BAT mitochondria, whereas physiological thermogenic activity is more appropriately indicated by GDP binding. The alterations in binding activity appear not to be due to changes in the mitochondrial membrane integrity.

scholarly journals Evidence for decreased GDP binding to brown-adipose-tissue mitochondria of obese Zucker (fa/fa) rats in the very first days of life

1984 ◽  
Vol 221 (1) ◽  
pp. 241-245 ◽  
Author(s):  
R Bazin ◽  
D Eteve ◽  
M Lavau
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Binding Sites ◽  
Scatchard Analysis ◽  
Zucker Rat ◽  
Large Decrease ◽  
Sequential Order ◽  
Lean Control ◽  
Brown Adipose ◽  
Obese Zucker Rat

GDP binding to brown-adipose-tissue mitochondria of obese Zucker-rat (fa/fa) pups aged 2-14 days was significantly less than in lean control rats. Scatchard analysis in 10-day-old pups suggests that there was a large decrease in GDP-binding sites. However, a significant increase in fat content in brown adipose tissue of 2-day-old pre-obese pups raised the question of the sequential order and causal relationship between these two derangements.

Control mechanisms in brown adipose tissue plasma membrane

1984 ◽  
Vol 62 (7) ◽  
pp. 631-636 ◽  
Author(s):  
N. Bégin-Heick ◽  
H. M. C. Heick
Keyword(s):  
Adipose Tissue ◽  
Plasma Membrane ◽  
Adenylate Cyclase ◽  
Brown Adipose Tissue ◽  
Heat Production ◽  
Metabolic Effects ◽  
Maximal Response ◽  
Obese Mouse ◽  
Control Mechanisms ◽  
Brown Adipose

It is generally agreed that the site of heat production during nonshivering thermogenesis is the brown adipose tissue (BAT) and that the triggering event for heat production is the interaction of noradrenaline (NA) with its receptor on the plasma membrane. Following this initial event, several changes occur which result in increased rates of cAMP synthesis, redistribution of ions across the membrane, enhanced rates of lipolysis, and increased mitochondrial oxidation of substrates. BAT is also a target for the anabolic effect of insulin. Available evidence shows that insulin receptors are present on the BAT plasma membrane and that insulin can oppose the metabolic effects of catecholamine on BAT. We have studied more particularly the response of BAT adenylate cyclase to catecholamines in an animal model (the ob/ob mouse) which has a defective thermogenic response. The capacity of adenylate cyclase to be stimulated by catecholamines was significantly less in the tissue of obese mice than in lean controls. To produce a response equal to the half-maximal response in the lean mouse, a 10-fold increase in the NA concentration was required in the BAT of the obese mouse. These results are in harmony with those of others showing that the lipolytic response to catecholamines is abnormal in the BAT of the obese mouse. The adenylate cyclase activity can be altered by changes in the lipid composition of the diet and by manipulation of hormone levels. It is likely that the alteration in adenylate cyclase responsiveness is one of the contributing factors in the impaired thermogenesis and obesity in this animal.

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