Epinephrine Binding to Rat Adipocytes and Their Subcellular Fractions<sup>1</sup>

Jarett, Leonard; Smith, Robert M.; Crespin, Stephen R.

doi:10.1210/endo-94-3-719

Cited by 23 publications

(10 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The Kds and specificity are similar to those reported for dog heart [3], rat adipocyte [1], and chick myoblast [2]. This binding differs, however, from the irreversible binding in several tissues and subcellular fractions demon strated by Cuatrecasas et al [7], M aguire et al [4], and Wolfe et al [12] which resulted from the presence of auto-oxidation products in their systems.…”

Section: Discussionsupporting

confidence: 80%

See 1 more Smart Citation

Reversible Norepinephrine Binding to Rabbit Myometrium: Relationship to Sites of Known Biological Significance

Roberts¹,

Keller²,

Goldfien³

1976

Gynecol Obstet Invest

View full text Add to dashboard Cite

Catecholamines bind specifically to several cell types and subcellular fractions. This binding is not consistent with binding to the adrenergic receptor. Catecholamines would be expected to bind to sites other than the adrenergic receptor (uptake 1, uptake 2, nerve vesicles, catecholamine-O-methyl transferase and serum albumin). We characterized the binding of ³H-norepinephrine to microsomes prepared from rabbit myometrium. In the presence of antioxidant binding was reversible and ³H-norepinephrine could be recovered bound to microsomes or free in incubation media. The binding was not characteristic of binding to any one known biological site. It may represent binding to a mixture of these sites or may be fortuitous binding to sites of unknown biological significance.

show abstract

Section: Discussionsupporting

confidence: 80%

“…Catecholamine binding has been described in a number of tissues and subcellular fractions [1][2][3][4][5][6][7][8][9][10][11][12][13]. The binding is quite similar in many of these preparations.…”

Section: Introductionmentioning

confidence: 99%

Reversible Norepinephrine Binding to Rabbit Myometrium: Relationship to Sites of Known Biological Significance

Roberts¹,

Keller²,

Goldfien³

1976

Gynecol Obstet Invest

View full text Add to dashboard Cite

show abstract

“…between the characteristics and behavior of insulin and lectin receptors, the more intriguing it becomes t o determine the commonality which produces many of the same physiological responses (19,31,32). The Fm-I complex should prove useful in such studies.…”

Section: Jss: 59mentioning

confidence: 99%

The natural occurrence of insulin receptors in groups on adipocyte plasma membranes as demonstrated with monomeric ferritin‐insulin

Jarett

Smith

1977

J Supramol Struct

Self Cite

View full text Add to dashboard Cite

This study w i s designed t o document whether the reported distribution o f insulin receptors in small groups of receptor sites randomly distributed in the glycocalyx of adipocytes and isolated adipocyte plasma membranes was a naturally occurring phenomena or due t o artifacts. Possible artifacts include: 1) oligomeric forms of ferritin in the ferritin-insulin preparation, 2) an uneven distribution of the glycocalyx on the plasma membrane, o r 3) ligand-induced aggregation of occupied receptor complexes. Biogel A 1.5m chromatography of the ferritin-insulin conjugate revealed the ferritin in the ferritin-insulin complex to consist of 55% monomers, 15% dimers, and 30% oligomers. The monomer peak was purified (> 95%) for use in these studies. Cationic ferritin, a glycocalyx marker, when incubated with paraformaldehyde-fixed plasma membranes. was found t o be uniformly distributed o n the surface of the plasma membrane indicative of uniformly distributed glycocalyx. The ability t o demonstrate and inhibit ligand-induced aggregation on the isolated plasma membrane was established with a multivalent ligand, ferritinconcanavalin A. More than 66% of the ferritin-concanavalin A receptors were found in large clusters of 5 or more and 34% as singletons o r clusters of up to 4 when incubated at 24°C with fresh membranes. Only 38% of the ferritin-concanavalin A receptors were in large clusters; 62% were singletons o r clusters up t o 4 on membranes prefixed with paraformaldehyde before incubation. The distribution of the monomeric ferritin-insulin was similar on both adipocytes and purified adipocyte plasma membranes and was consistent with earlier reports with ferritin-insulin. The quantitative distribution of the monomeric ferritin-insulin as singletons or in groups of 2-6 was comparable between the intact cells and isolated membranes incubated at 24°C. The binding of 500 p u n i t s monomeric ferritin-insulin per ml t o the isolated plasma membranes was studied under incubation conditions similar t o those used with ferritin-concanavalin A. Under all three conditions, fresh membranes at 24°C and 0--4"C and prefixed membranes at 24"C, the pattern of distribution of the monomeric ferritin-insulin as singletons o r groups of 1-6 was identical, indicating that the ligand was not causing aggregation into clusters as did the concanavalin A . Thus, the occurrence of insulin receptors in small groups appears t o be a natural phenomenon in the plasma membrane structure of adipocytes.

show abstract

“…3). And finally, two agents that are known to mimic insulin action on various processes in the intact cell, concanavalin A (12,13) and antibody to insulin receptor (5), produce the same effect as insulin on pyruvate dehydrogenase in this system (Fig. 4).…”

Section: Discussionmentioning

confidence: 88%

“…The biological significance of the insulin effect in the plasma membrane/mitochondria mixture is suggested by the observation that two agents that mimic insulin action in adipocytes, concanavalin A (12,13) and antibody to insulin receptor (5), also stimulate pyruvate dehydrogenase activity (Fig. 4).…”

Section: Discussionmentioning

confidence: 99%

Activation of pyruvate dehydrogenase by direct addition of insulin to an isolated plasma membrane/mitochondria mixture: Evidence for generation of insulin's second messenger in a subcellular system

Seals

Jarett

1980

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

147

View full text Add to dashboard Cite

The addition of insulin to a mixture of plasma membrane and mitochondrial fractions from rat adipocytes results in a decrease in the phosphorylation of a mitochondrial protein identified as the a subunit of pyruvate dehydrogenase [pyruvate:lipoamide oxidoreductase (decarboxylating and acceptor-acetylating), EC 1.2.4.11 (Seals, J. R., McDonald, J. M. & Jarett, L. (1979) J. BioL Chem. 254,[6991][6992][6993][6994][6995][6996]. This study confirms the prediction that a corresponding increase in pyruvate dehydrogenase activity can be effected by insulin treatment of this preparation. Incubation of the plasma membrane/mitochondria mixture with ATP inhibited pyruvate dehydrogenase activity as measured in a subsequent enzyme assay. The presence of insulin during this incubation with ATP resulted in a 24.5% stimulation of enzyme activity compared to incubation without insulin (n = 9, P < 0.001). The effect was specific for biologically active insulin and was insulin dose-dependent in the physiological range of insulin. Supermaximal doses of insulin produced reduced effects. An insulin effect of similar magnitude could also be observed when the plasma membrane/mitochondria mixture was incubated without ATP. Two insulin mimickers, concanavalin A and antibody to insulin receptor, stimulated pyruvate dehydrogenase by 30.4% (n = 6, P < 0.001) and 28.1% (n = 8, P < 0.001), respectively. Both of these agents also produced reduced effects at supermaximal concentrations. The effects of all three agents required plasma membranes and could not be produced by treatment of mitochondria alone. The results suggest that a mechanism common to all three agents is responsible for transmitting the stimulation from the plasma membrane to the mitochondrial components of the mixture.Analysis of the mechanism of insulin action on its target cells has been hindered by the complex interactions among metabolic and regulatory factors in the intact cell. However, insulin action has recently been demonstrated in a simplified subcellular system consisting of a mixture of purified plasma membrane and mitochondrial fractions from the rat adipocyte (1, 2). Addition of insulin to this subcellular system caused a plasma membrane-mediated decrease in the phosphorylation of a mitochondrial protein, identified as the a subunit of pyruvate dehydrogenase [pyruvate:lipoamide oxidoreductase (decarboxylating and acceptor-acetylating), EC 1.2.4.1]. This effect was consistent with the proposed model of insulin action on pyruvate dehydrogenase in the intact cell (3, 4). From these data, it was predicted that the activity of pyruvate dehydrogenase should be stimulated by the addition of insulin to the plasma membrane/mitochondria mixture. This study investigates the activity of pyruvate dehydrogenase in the plasma membrane/mitochondria mixture and the effect of insulin and other agents on this enzyme. EXPERIMENTAL PROCEDURESMaterials. Male Sprague-Dawley rats (120 g) were obtained from Eldridge Laboratory Animals (Barnhardt, MO). Collagenase, bovine serum alb...

show abstract

Epinephrine Binding to Rat Adipocytes and Their Subcellular Fractions¹

Cited by 23 publications

References 0 publications

Reversible Norepinephrine Binding to Rabbit Myometrium: Relationship to Sites of Known Biological Significance

Reversible Norepinephrine Binding to Rabbit Myometrium: Relationship to Sites of Known Biological Significance

The natural occurrence of insulin receptors in groups on adipocyte plasma membranes as demonstrated with monomeric ferritin‐insulin

Activation of pyruvate dehydrogenase by direct addition of insulin to an isolated plasma membrane/mitochondria mixture: Evidence for generation of insulin's second messenger in a subcellular system

Contact Info

Product

Resources

About

Epinephrine Binding to Rat Adipocytes and Their Subcellular Fractions1

Cited by 23 publications

References 0 publications

Reversible Norepinephrine Binding to Rabbit Myometrium: Relationship to Sites of Known Biological Significance

Reversible Norepinephrine Binding to Rabbit Myometrium: Relationship to Sites of Known Biological Significance

The natural occurrence of insulin receptors in groups on adipocyte plasma membranes as demonstrated with monomeric ferritin‐insulin

Activation of pyruvate dehydrogenase by direct addition of insulin to an isolated plasma membrane/mitochondria mixture: Evidence for generation of insulin's second messenger in a subcellular system

Contact Info

Product

Resources

About

Epinephrine Binding to Rat Adipocytes and Their Subcellular Fractions¹