scholarly journals Studies on the α-subunit of bovine brain S-100 protein

1984 ◽  
Vol 218 (3) ◽  
pp. 691-696 ◽  
Author(s):  
H R Masure ◽  
J F Head ◽  
H M Tice
Keyword(s):  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Fluorescence Emission ◽  
Bovine Brain ◽  
Alpha Subunit ◽  
Tryptophan Residue ◽  
Affinity Column ◽  
Apparent Dissociation Constant ◽  
Α Subunit ◽  
S 100

A method is described for the rapid purification of both S-100 protein and calmodulin from crude bovine brain extracts by the use of a fluphenazine-Sepharose affinity column eluted stepwise with decreasing concentrations of free Ca2+. Protein containing only alpha-subunit was purified from preparations of S-100 protein by anion-exchange chromatography. This protein co-migrated with the alpha-subunit of S-100 protein on sodium dodecyl sulphate/urea/polyacrylamide-gel electrophoresis and had an amino acid composition identical with that previously reported for this subunit. The results of u.v.-absorption and fluorescence-emission spectroscopy indicate that the tryptophan residue of the purified alpha-subunit of S-100 protein undergoes a Ca2+-induced change in environment. Measurements of changes in tryptophan fluorescence with increasing Ca2+ concentrations suggest an apparent dissociation constant of the alpha-subunit for Ca2+ of 7 × 10(-5)M in the absence of K+. In the presence of 90mM-K+ this value is increased to 3.4 × 10(-4)M.

scholarly journals Prolyl 4-hydroxylase from Volvox carteri. A low-Mr enzyme antigenically related to the α subunit of the vertebrate enzyme

1988 ◽  
Vol 256 (1) ◽  
pp. 257-263 ◽  
Author(s):  
D D Kaska ◽  
R Myllylä ◽  
V Günzler ◽  
A Gibor ◽  
K I Kivirikko
Keyword(s):  
Green Alga ◽  
Polyacrylamide Gel Electrophoresis ◽  
Beta Subunit ◽  
Alpha Subunit ◽  
Affinity Column ◽  
Major Protein ◽  
Volvox Carteri ◽  
Chlamydomonas Reinhardii ◽  
Α Subunit ◽  
Major Protein Band

Prolyl 4-hydroxylase was isolated in a highly purified form from a multi-cellular green alga, Volvox carteri, by a procedure consisting of ion-exchange chromatography and affinity chromatography on poly(L-hydroxyproline) coupled to Sepharose. Two other affinity-column procedures were also developed, one involving 3,4-dihydroxyphenylacetate and the other 3,4-dihydroxyphenylpropionate linked to Sepharose. The Km values of the Volvox enzyme for the co-substrates and the peptide substrate, as well as the inhibition constants for selected 2-oxoglutarate analogues, were similar to those of the enzyme from Chlamydomonas reinhardii, except that the Km for 2-oxoglutarate with the Volvox enzyme was 6-fold greater. The temperature optimum of the Volvox enzyme was also 10 degrees C higher. The apparent Mr of the Volvox enzyme by gel filtration was about 40,000, being similar to that reported for the Chlamydomonas enzyme but markedly lower than that of the vertebrate enzymes. A similar apparent Mr of about 40,000 was also found for prolyl 4-hydroxylase from the green alga Enteromorpha intestinalis, whereas the enzyme from various vascular plants gave an apparent Mr greater than 300,000. SDS/polyacrylamide-gel electrophoresis demonstrated in the highly purified Volvox enzyme the presence of a major protein band doublet with a Mr of about 65,000 and a minor doublet of Mr about 55,000-57,000. A polyclonal antiserum, prepared against the Mr-65,000 doublet, stained in immunoblotting the Mr-65,000 doublet as well as the alpha subunit, but not the beta subunit, of the vertebrate prolyl 4-hydroxylase. An antiserum against the beta subunit of the vertebrate enzyme stained in immunoblotting a Mr-50,000 polypeptide in a partially purified Volvox enzyme preparation, but did not stain either the Mr-65,000 or the Mr-55,000-57,000 doublet of the highly purified enzyme. The data thus suggest that the active Volvox carteri prolyl 4-hydroxylase is an enzyme monomer antigenically related to the alpha subunit of the vertebrate enzyme.

scholarly journals Studies on the incorporation of [32P]phosphate into pyruvate dehydrogenase in intact rat fat-cells. Effects of insulin

1980 ◽  
Vol 192 (2) ◽  
pp. 469-481 ◽  
Author(s):  
W A Hughes ◽  
R W Brownsey ◽  
R M Denton
Keyword(s):  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Complex ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Subcellular Fractionation ◽  
Alpha Subunit ◽  
Fat Cells ◽  
Phosphorylated Proteins ◽  
Alpha Subunits ◽  
Dehydrogenase Complex

1. Intact rat epididymal fat-cells were incubated with 32Pi, and the intracellular proteins were separated by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. One of the separated bands of phosphorylated proteins had an apparent subunit mol.wt. of 42 000, which is the same as that of the alpha-subunit of the pyruvate dehydrogenase complex. By using a combination of subcellular fractionation, immunoprecipitation with antiserum raised against pyruvate dehydrogenase complex and two-dimensional electrophoresis it was apparent that the incorporation into alpha-subunits accounted for 35–45% of the total incorporation into this band of phosphoproteins. 2. The increase in the initial activity of pyruvate dehydrogenase that follows brief exposure of fat-cells to insulin was shown to be associated with a decrease in the steady-state incorporation of 32P into the alpha-subunits of pyruvate dehydrogenase. 3. Tryptic peptide analysis of pyruvate dehydrogenase [32P]phosphate, labelled in intact fat-cells, indicated that three serine residues on the alpha-subunit were phosphorylated, corresponding to the three sites phosphorylated when purified pig heart pyruvate dehydrogenase was incubated with [gamma-32P]ATP. The relative phosphorylation of all three serine residues appeared to be similar in 32P-labelled alpha-subunits in both control and insulin-treated fat-cells.

Purification and characterization of a novel factor which stimulates rat ribosomal gene transcription in vitro by interacting with enhancer and core promoter elements

1990 ◽  
Vol 10 (10) ◽  
pp. 5177-5186
Author(s):  
J Zhang ◽  
S T Jacob
Keyword(s):  
Ribosomal Dna ◽  
Core Promoter ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Affinity Column ◽  
Mobility Shift ◽  
Enhancer Element ◽  
Molecular Weights ◽  
The Core ◽  
Pol I

Previous studies in our laboratory have characterized a 174-base-pair (bp) enhancer sequence in the rat ribosomal DNA spacer region that exhibits all of the characteristics of a polymerase (Pol) II enhancer. Further studies showed that at least half of the enhancer activity resides in a 37-bp motif (E1) within the 174-bp spacer sequence that is located between positions -2.183 and -2.219 kilobase pairs upstream of the initiation site. To identify the factor(s) that binds specifically to the 37-bp enhancer domain, we fractionated whole-cell extract from rat adenocarcinoma ascites cells by chromatography on a series of columns, including an oligodeoxynucleotide affinity column. The final preparation contained two polypeptides of molecular weights 79,400 and 89,100 and was completely devoid of RNA Pol I activity. Electrophoretic mobility shift analysis showed that the polypeptides in the purified preparation (designated E1BF) interacted with both the enhancer element and the core promoter. To determine whether each polypeptide can separately bind to the core promoter and the enhancer, the individual components were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, renatured, and subjected to gel retardation analysis. This experiment demonstrated that both polypeptides interacted with the two cis-acting sequences. The specificity of the binding was demonstrated by competition with unlabeled 37-bp and core promoter fragments and lack of competition with nonspecific DNAs in the mobility shift assay. The 37-bp enhancer as well as the downstream sequence of the core promoter were protected by E1BF in the DNase I footprinting assay. Addition of E1BF to limiting amounts of fraction DE-B, which contains all factors essential for Pol I-directed transcription, resulted in three- to fourfold stimulation of ribosomal DNA transcription. Comparison of molecular weights and footprinting profiles did not reveal any relationship between E1BF and other Pol I trans-acting factors.

Rabphilin-3A, a putative target protein for smg p25A/rab3A p25 small GTP-binding protein related to synaptotagmin

1993 ◽  
Vol 13 (4) ◽  
pp. 2061-2068
Author(s):  
H Shirataki ◽  
K Kaibuchi ◽  
T Sakoda ◽  
S Kishida ◽  
T Yamaguchi ◽  
...  
Keyword(s):  
Binding Protein ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Bovine Brain ◽  
Target Protein ◽  
Dependent Manner ◽  
Gtp Binding Protein ◽  
Reading Frame ◽  
Gtp Binding ◽  
Putative Target

In a previous study (H. Shirataki, K. Kaibuchi, T. Yamaguchi, K. Wada, H. Horiuchi, and Y. Takai, J. Biol. Chem. 267:10946-10949, 1992), we highly purified from bovine brain crude membranes the putative target protein for smg p25A/rab3A p25, a ras p21-related small GTP-binding protein implicated in neurotransmitter release. In this study, we have isolated and sequenced the cDNA of this protein from a bovine brain cDNA library. The cDNA had an open reading frame encoding a protein of 704 amino acids with a calculated M(r) of 77,976. We tentatively refer to this protein as rabphilin-3A. Structural analysis of rabphilin-3A revealed the existence of two copies of an internal repeat that were homologous to the C2 domain of protein kinase C as described for synaptotagmin, which is known to be localized in the membrane of the synaptic vesicle and to bind to membrane phospholipid in a Ca(2+)-dependent manner. The isolated cDNA was expressed in COS7 cells, and the encoded protein was recognized with an anti-rabphilin-3A polyclonal antibody and was identical in size with rabphilin-3A purified from bovine brain by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Moreover, both rabphilin-3A purified from bovine brain and recombinant rabphilin-3A made a complex with the GTP gamma S-bound form of rab3A p25 but not with the GDP-bound form of rab3A p25. Immunoblot and Northern (RNA) blot analyses showed that rabphilin-3A was highly expressed in bovine and rat brains. These results indicate that rabphilin-3A is a novel protein that has C2 domains and selectively interacts with the GTP-bound form of rab3A p25.

scholarly journals Purification and characterization of a novel factor which stimulates rat ribosomal gene transcription in vitro by interacting with enhancer and core promoter elements.

1990 ◽  
Vol 10 (10) ◽  
pp. 5177-5186 ◽  
Author(s):  
J Zhang ◽  
S T Jacob
Keyword(s):  
Ribosomal Dna ◽  
Core Promoter ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Affinity Column ◽  
Mobility Shift ◽  
Enhancer Element ◽  
Molecular Weights ◽  
The Core ◽  
Pol I

Previous studies in our laboratory have characterized a 174-base-pair (bp) enhancer sequence in the rat ribosomal DNA spacer region that exhibits all of the characteristics of a polymerase (Pol) II enhancer. Further studies showed that at least half of the enhancer activity resides in a 37-bp motif (E1) within the 174-bp spacer sequence that is located between positions -2.183 and -2.219 kilobase pairs upstream of the initiation site. To identify the factor(s) that binds specifically to the 37-bp enhancer domain, we fractionated whole-cell extract from rat adenocarcinoma ascites cells by chromatography on a series of columns, including an oligodeoxynucleotide affinity column. The final preparation contained two polypeptides of molecular weights 79,400 and 89,100 and was completely devoid of RNA Pol I activity. Electrophoretic mobility shift analysis showed that the polypeptides in the purified preparation (designated E1BF) interacted with both the enhancer element and the core promoter. To determine whether each polypeptide can separately bind to the core promoter and the enhancer, the individual components were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, renatured, and subjected to gel retardation analysis. This experiment demonstrated that both polypeptides interacted with the two cis-acting sequences. The specificity of the binding was demonstrated by competition with unlabeled 37-bp and core promoter fragments and lack of competition with nonspecific DNAs in the mobility shift assay. The 37-bp enhancer as well as the downstream sequence of the core promoter were protected by E1BF in the DNase I footprinting assay. Addition of E1BF to limiting amounts of fraction DE-B, which contains all factors essential for Pol I-directed transcription, resulted in three- to fourfold stimulation of ribosomal DNA transcription. Comparison of molecular weights and footprinting profiles did not reveal any relationship between E1BF and other Pol I trans-acting factors.

Studies of human pituitary LH containing internally cleaved β subunit

1991 ◽  
Vol 6 (1) ◽  
pp. 101-109 ◽  
Author(s):  
A. Stockell Hartree ◽  
R. C. Shownkeen
Keyword(s):  
Receptor Binding ◽  
Proteolytic Enzyme ◽  
Enzyme Inhibitor ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Peptide Bond ◽  
Β Subunit ◽  
Human Pituitary ◽  
Α Subunit ◽  
Peptide Bond Cleavage

ABSTRACT We have investigated the origin of the internal peptide bond cleavage found in the β subunit of a proportion of pituitary human LH (hLH) molecules, as well as the effects of this cleavage (or nick) on the interaction between α and β subunits and on binding of hLH to its receptor. The content of cleaved β subunit, assessed by the intensity of staining of an approximately 10 kDa component on sodium dodecyl sulphate-polyacrylamide gel electrophoresis of reduced hLH, was variable in batches of hLH prepared from pooled acetone-preserved human pituitary glands. There was evidence of a similar cleavage in purified hTSH, but not in the purified hFSH or human chorionic gonadotrophin examined. Although intact hLH was relatively resistant to cleavage in solution, urea dissociation of hormone followed by dialysis resulted in an increased content of nicked β subunit, which was largely prevented by incorporation of the proteolytic enzyme inhibitor phenylmethylsulphonyl fluoride (PMSF) and the metal-chelating agent EDTA. Hormone that was virtually free of nicked β subunit was obtained by urea dissociation of hLH subunits in the presence of PMSF and EDTA followed by dialysis to remove urea, reassociation of subunits at 37 °C (pH 7) and purification of reassociated hLH dimer by gel filtration on Sephadex G-100 in the presence of 1-anilinonaphthalene-8-sulphonic acid (ANS). When hLH was incubated at 37 °C at pH 55 or pH 95 in the absence of enzyme inhibitors, some cleaved β subunit was found in the hLH—ANS dimer form of the hormone, but most of the nicked subunit appeared in fractions of lower molecular weight and with low receptor-binding activity. Fractions isolated as hLH—ANS dimer had receptor-binding activities which were negatively correlated with their content of cleaved β subunit, the most active fraction (21 000 i.u./mg) being virtually free of this component. Our studies suggest (1) that the cleavage is caused by proteolytic enzyme activity present in human pituitary tissue and in purified preparations of hLH, (2) that free hLH-β subunit is cleaved far more readily than when it is combined with α subunit in the intact hormone, (3) that the presence of the cleavage in free hLH-β prevents refolding of this subunit to the correct conformation that permits its combination with α subunit to regenerate native hormone, and (4) that the site of cleavage is likely to be at a peptide bond located on the surface of the intact hLH molecule.

scholarly journals Gangliosides and sialosylglycoproteins in coated vesicles from bovine brain

1985 ◽  
Vol 225 (3) ◽  
pp. 713-721 ◽  
Author(s):  
D Gravotta ◽  
H J F Maccioni
Keyword(s):  
Rat Brain ◽  
Plasma Membranes ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Bovine Brain ◽  
Coated Vesicles ◽  
Molar Ratio ◽  
Coated Vesicle ◽  
Synaptic Plasma Membranes ◽  
Morphological Criteria

The content of gangliosides and sialosylglycoproteins was investigated in a coated-vesicle-enriched fraction prepared from bovine brain by the method of Pearse [(1975) J. Mol. Biol. 97, 93-98] and further purified by g.p.c. (glass-permeation chromatography) [Pfeffer & Kelly (1981) J. Cell Biol. 91, 385-391]. From morphological criteria and from the analysis of the polypeptide pattern on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis the coated-vesicle fraction (CV-fraction) appeared more than 95% pure. The ganglioside-NeuAc (N-acetylneuraminate), glycoprotein-NeuAc, phospholipid and cholesterol contents of CV-fraction were compared with those of bovine brain synaptic plasma membranes (SPM). The cholesterol to phospholipid molar ratio was 0.47 +/- 0.07 in CV-fraction and 1.06 +/- 0.08 in SPM. The ganglioside-NeuAc and glycoprotein-NeuAc to phospholipid molar ratios were 0.047 and 0.020 respectively in CV-fraction and 0.039 and 0.016 respectively in SPM. The (Na+ + K+)-dependent ATPase activity sensitive to ouabain (in mumol of Pi/h per nmol of phospholipid) was 1.04 in CV-fraction and 0.63 in SPM; the ratio between this activity and the activity resistant to ouabain was 2 in CV-fraction and 1.4 in SPM. A t.l.c. analysis of the ganglioside fractions showed that most of the ganglioside species present in SPM were present in CV-fraction. In a rat brain coated-vesicle preparation not subjected to g.p.c., the activities [as sugar-radioactivity (c.p.m.) transferred/h per mumol of phospholipid] of the enzymes CMP-NeuAc:sialosyl-lactosylceramide (GM3) sialosyl-, UDP-Gal:N-acetylgalactosaminyl(sialosyl)lactosylceramide (GM2) galactosyl- and UDP-GalNAc:sialosyl-lactosylceramide (GM3) N-acetylgalactosaminyl-transferases, which were considered Golgi-apparatus markers, were about 19, 16 and 10% respectively of those determined in rat brain neuronal perikaryon-enriched fractions. Taken together, the results indicate that most of the major gangliosides are constituents of coated vesicles.

Purification and properties of human placental NADPH–cytochrome P-450 reductase

1986 ◽  
Vol 64 (3) ◽  
pp. 184-193 ◽  
Author(s):  
Norio Muto ◽  
Liat Tan
Keyword(s):  
Salt Concentration ◽  
High Performance ◽  
Specific Activity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Visible Region ◽  
Relative Mass ◽  
Affinity Column ◽  
Nadph Cytochrome ◽  
Cytochrome P 450

Human placental NADPH–cytochrome P-450 reductase (EC 1.6.2.4) was purified to electrophoretic homogeneity in two chromatographic steps with a high retention of bioactivity. After solubilization with 1% sodium cholate in a protective medium containing 20% glycerol, 10 μM 4-androstene-3, 17-dione, 1 mM dithiothreitol, and 0.2 mM EDTA, a 35–60% ammonium sulfate precipitate was prepared. The crude protein mixture was then applied to a 2′, 5′-ADP–Sepharose 4B affinity column, followed by high-performance anion-exchange chromatography (Pharmacia Mono-Q column). Two forms of the reductase were isolated. One was eluted at higher salt concentration and had a relative mass (Mr) of 79 kdaltons (kDa) as estimated by sodium dodecyl sulfate – polyacrylamide gel electrophoresis and high-performance gel permeation chromatography. A smaller size reductase with a Mr of 70 kDa, eluting at lower salt concentration, was also formed by trypsinolyis of the 79-kDa reductase. It must therefore be regarded as a proteolytic artifact. The absolute spectra in the visible region of the two reductases were identical with maxima at 376 and 452 nm, typical of a flavoprotein. They also had the same specific activity of 24.7 ± 0.7 μmol/min per milligram protein towards cytochrome c. However, only the 79-kDa reductase showed aromatase-reconstitution activity. The homogeneity of these reductases was further confirmed by the appearance of a single peak when subjected to gradient, reversed-phase high-performance liquid chromatography. According to its amino acid composition, the 79-kDa reductase is a highly acidic and hydrophobic protein, composed of 695 residues.

scholarly journals Saturation Mutagenesis of Toluene ortho-Monooxygenase of Burkholderia cepacia G4 for Enhanced 1-Naphthol Synthesis and Chloroform Degradation

2004 ◽  
Vol 70 (6) ◽  
pp. 3246-3252 ◽  
Author(s):  
Lingyun Rui ◽  
Young Man Kwon ◽  
Ayelet Fishman ◽  
Kenneth F. Reardon ◽  
Thomas K. Wood
Keyword(s):  
Burkholderia Cepacia ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Saturation Mutagenesis ◽  
Wild Type ◽  
Oxidation Activity ◽  
Α Subunit ◽  
Whole Cells ◽  
Elevated Expression ◽  
Naphthalene Oxidation

ABSTRACT Directed evolution of toluene ortho-monooxygenase (TOM) of Burkholderia cepacia G4 previously created the hydroxylase α-subunit (TomA3) V106A variant (TOM-Green) with increased activity for both trichloroethylene degradation (twofold enhancement) and naphthalene oxidation (six-times-higher activity). In the present study, saturation mutagenesis was performed at position A106 with Escherichia coli TG1/pBS(Kan)TOMV106A to improve TOM activity for both chloroform degradation and naphthalene oxidation. Whole cells expressing the A106E variant had two times better naphthalene-to-1-naphthol activity than the wild-type cells (V max of 9.3 versus 4.5 nmol � min−1 � mg of protein−1 and unchanged Km ), and the regiospecificity of the A106E variant was unchanged, with 98% 1-naphthol formed, as was confirmed with high-pressure liquid chromatography. The A106E variant degrades its natural substrate toluene 63% faster than wild-type TOM does (2.12 � 0.07 versus 1.30 � 0.06 nmol � min−1 � mg of protein−1 [mean � standard deviation]) at 91 μM and has a substantial decrease in regiospecificity, since o-cresol (50%), m-cresol (25%), and p-cresol (25%) are formed, in contrast to the 98% o-cresol formed by wild-type TOM. The A106E variant also has an elevated expression level compared to that of wild-type TOM, as evidenced by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Another variant, the A106F variant, has 2.8-times-better chloroform degradation activity based on gas chromatography (V max of 2.61 versus 0.95 nmol � min−1 � mg of protein−1 and unchanged Km ) and chloride release (0.034 � 0.002 versus 0.012 � 0.001 nmol � min−1 � mg of protein−1). The A106F variant also was expressed at levels similar to those of wild-type TOM and 62%-better toluene oxidation activity than wild-type TOM (2.11 � 0.3 versus 1.30 � 0.06 nmol � min−1 � mg of protein−1). A shift in regiospecificity of toluene hydroxylation was also observed for the A106F variant, with o-cresol (28%), m-cresol (18%), and p-cresol (54%) being formed. Statistical analysis was used to estimate that 292 colonies must be screened for a 99% probability that all 64 codons were sampled during saturation mutagenesis.

scholarly journals The adipocyte Goα-immunoreactive polypeptide is different from the α subunit of the brain Go protein

1989 ◽  
Vol 260 (1) ◽  
pp. 307-310 ◽  
Author(s):  
B Rouot ◽  
J Carrette ◽  
M Lafontan ◽  
P Lan Tran ◽  
J A Fehrentz ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Molecular Mass ◽  
G Protein ◽  
Polyacrylamide Gel Electrophoresis ◽  
Mass Range ◽  
Alpha Subunit ◽  
Α Subunit ◽  
Positive Immunoreactivity ◽  
Rat Adipose Tissue ◽  
The Brain

Rat adipose tissue possesses two Bordetella pertussis toxin (PTX) substrates and, in the same 39-41 kDa molecular mass range, positive immunoreactivity has also been reported with antibodies against the alpha subunit of Go, the major brain GTP-binding protein (G-protein). In this study, the presence of the brain Go alpha subunit at 39 kDa in adipocytes was reassessed, since direct correspondence between PTX substrates and Go alpha immunoreactivity has not yet been clearly established. On resolutive SDS/polyacrylamide-gel electrophoresis, the PTX substrates of human adipocytes were compared with the three PTX substrates found in brain. No ADP-ribosylated substrate at the level of the 39 kDa brain Go alpha could be detected in adipocyte membranes. Immunoblotting of human adipocyte membranes stained with our anti-Go alpha antibodies confirmed the presence of a positive immunoreactivity in this tissue, but the apparent molecular mass of the immunoreactive polypeptide in adipocytes was higher than that found in nervous tissues. Taken together, these results indicate that the brain Go alpha subunit is not present in adipose tissue. They also suggest the existence of a G-protein in adipocytes which is immunologically related to Go alpha but having a slightly higher molecular mass.

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