A specific radioimmunoassay has been established for a growth hormone-dependent insulinlike factor (IGF) binding protein (BP) from human plasma. Although the assay was directed against 53-kD, acid-stable BP subunit, main immunoreactive in circulation had an apparent molecular mass of approximately 125 kD. Only higher primate species showed cross-reactivity, and IGF-I, IGF-II, other peptides were without effect. Circulating levels healthy subjects rose threefold early childhood to puberty. In...

N-terminal as well internal amino acid sequence data were obtained from the GH dependent, insulinlike growth factor (IGF) binding protein, BP-53, purified human plasma. Based on these data, full-length cDNA clones of BP-53 have been isolated, and complete deduced determined. This contains a 27 putative signal followed by mature protein 264 acids containing 18 cysteine residues clustered near N- C-terminus. The has 33% identity including conservation all with recently cloned BP-28, smaller...

Insulin-like growth factor (1GF)-binding protein (BP) has been purified from Cohn fraction IV of human plasma by acidification, ion exchange to remove endogenous ligands, and affinity chromatography on agarose-IGF-11.The pure appeared as a single peak high performance reverse-phase gel permeation (molecular mass, 45-50 kDa), but sodium dodecyl sulfate-polyacrylamide electrophoresis gave major band at 53 kDa minor 47 kDa, unreduced, or 43 40 respectively, reduced.The two bands stained for...

The 6 high-affinity insulin-like growth factor binding proteins (IGFBPs) are multifunctional that modulate cell signaling through multiple pathways. Their canonical function at the cellular level is to impede access of (IGF)-1 and IGF-2 their principal receptor IGF1R, but IGFBPs can also inhibit, or sometimes enhance, IGF1R either own post-translational modifications, such as phosphorylation limited proteolysis, by interactions with other regulatory proteins. Beyond regulation activity, have...

The use of growth hormone (GH) as an anabolic agent is limited by its tendency to cause hyperglycemia and inability reverse nitrogen wasting in some catabolic conditions. In a previous study comparing the actions GH IGF-I (insulin-like factor I), we observed that intravenous infusions (12 micrograms/kg ideal body wt [IBW]/h) attenuated degree comparable given subcutaneously at standard dose 0.05 mg/kg IBW per d. IGF-I, however, had hypoglycemia. present study, treated seven calorically...

Abstract In the human circulation, insulin-like growth factors (IGFs) circulate as part of a hormone-dependent 125- to 150-kDa complex. This complex has been postulated contain, in addition IGFs and one or more IGF-binding proteins, an acid-labile subunit (ALS) which does not itself bind IGFs. this study, ALS purified 1600-fold from serum, its binding properties have examined. Fresh serum was fractionated on DEAE-Sephadex, active fractions (determined by radioimmunoassay) were affinity...

To determine the structure of high molecular weight, growth hormone-dependent complex between insulin-like factors (IGF-I and IGF-II) their binding proteins in human serum, we have reconstituted from its purified component analyzed it by gel electrophoresis autoradiography after covalent cross-linking. The tested reconstitution mixtures were an acid-labile Mr 84,000-86,000 glycoprotein doublet (alpha subunit), acid-stable 47,000-53,000 with IGF-binding activity (BP-53 or beta IGF-I IGF-II...

Although insulin-like growth factor-binding protein (IGFBP)-3 and IGFBP-5 are known to modulate cell by reversibly sequestering extracellular factors, several reports have suggested that IGFBP-3, possibly also IGFBP-5, important factor-independent effects on growth. These may be related the putative nuclear actions of IGFBP-3 which we recently shown transported nuclei T47D breast cancer cells. We now describe mechanism for import IGFBP-5. In digitonin-permeabilized cells, where envelope...

Insulin-like growth factor-binding proteins (IGFBPs) play an integral role in modifying insulin-like factor actions a wide variety of cell types. Recent evidence suggests that IGFBP-3 and IGFBP-5 also have effects on are factor-independent. In investigating possible mechanisms for this effect, the intracellular trafficking IGFBP-5, both which contain sequences with potential nuclear localization, was studied T47D cells. Nuclear uptake fluorescently labeled observed proportion cells appeared...

We have determined the consequences of insulin-like growth factor-binding protein-1 (IGFBP-1) administration alone and in combination with factor-I (IGF-I). Human recombinant IGF-I, infused as a bolus into male Wistar rats, induced fall plasma glucose to 72 +/- 3% baseline 15 min after injection. Co-infusion equimolar concentrations human IGFBP-1 abolished IGF-I-induced (P less than 0.001). Injection caused rise levels 0.002). The half life IGFBP-1, measured using primate-specific RIA, was...

A RIA is described for the acid-labile (α) subunit of high mol wt insulin-like growth factor (IGF)-binding protein complex, a glycoprotein approximately 85,000 daltons (∼85K) which combines with GH-dependent binding (BP-53 or IGFBP-3) and IGF-I IGF-II to form complex. The assay shows relative specificity higher primate species. Whereas amniotic fluid, cerebrospinal seminal plasma contain virtually no immunoreactive a-subunit, easily detectable in 0.5-μL serum samples. Serum α-subunit levels...

The insulin-like growth factors (IGFs) circulate predominantly in a 150,000-dalton (150K) complex, the IGFbinding component of which appears to be an acid-stable 53K glycoprotein (BP-53). This study tested hypothesis that acid-labile subunit (ALS) reacts with binding form 150K complex. ALS activity was quantitated by conversion covalent BP-53-[125I]IGF-I tracer from about 60K 150K. DEAE-Sephadex chromatography serum at pH 8.2 yielded separate peaks 30–60K BP-53 immunoreactivity and 100–110K...

GH abuse by elite athletes is currently undetectable. To define suitable markers of doping, we assessed the effects acute exercise, administration, and withdrawal on GH/insulin-like growth factor (IGF) axis in athletic adult males. Acute endurance-type exercise increased serum GH, GH-binding protein (GHBP), total IGF-I, IGF-binding (IGFBP)-3, acid-labile subunit (ALS), each peaking at end exercise. IGFBP-1 after was completed. Free IGF-I did not change with Recombinant human treatment (0.15...

Protracted critical illness is marked by protein wasting resistant to feeding, accumulation of fat stores, and suppressed pulsatile release GH TSH. We previously showed that the latter can be reactivated brief infusion GH-releasing peptide (GHRP-2) TRH. Here, we studied combined GHRP-2 TRH for 5 days, which allowed a limited evaluation metabolic effectiveness this novel trophic endocrine strategy. Fourteen patients (mean ± sd age, 68 11 yr), critically ill 40 28 were compared matched group...

Somatogenic (i.e. GH) receptors have been studied on liver microsomal membranes from male and female rats. Tracer bovine GH was displaced its binding sites by GHs of various species, but only weakly PRLs. Specific 3.5-fold higher to rat than males. Streptozotocin-induced diabetes significantly reduced binding, 80% in females 50% males, while insulin therapy normalize weight gain reversed the decrease binding. Competitive curves were consistent with two independent classes site: low affinity...

An antibody raised against the major insulin-like growth factor (IGF)-binding protein in amniotic fluid (BP-28) was used to measure levels of a cross-reacting human plasma by RIA. Plasma BP-28 immunoreactivity had an apparent mol wt 35,000 high performance permeation chromatography. Sampled hourly for 12- or 24-h periods 15 children with wide range GH secretory activity, showed marked diurnal cycle, rising 10- 20-fold between 2400 and 0600 h peak 50–500 μ/L, then falling basal (0–40 μg/L)...

We report that transfection of insulin-like growth factor-binding protein-3 (IGFBP-3) cDNA in human breast cancer cell lines expressing either mutant p53 (T47D) or wild-type (MCF-7) induces apoptosis. IGFBP-3 also increases the ratio pro-apoptotic to anti-apoptotic members Bcl-2 family. In MCF-7, an increase Bad and Bax protein expression a decrease Bcl-x_L mRNA were observed. T47D, proteins up-regulated; is undetectable these cells. As T47D expresses protein, modulations induction...

Metformin decreases endogenous glucose production by the liver. Few studies have examined effect of metformin on insulin-signaling pathway in liver models, and none presented data normal human Huh7 hepatoma cells primary hepatocytes were used. Insulin receptor (IR) IR substrates (IRS)-1 -2 assessed immunoprecipitation immunoblot. Normal was used to assay kinase activity (IR-KA). Tyrphostin AG1024 inhibit IR-KA examine effects deoxyglucose uptake. (1 micro g/ml) increased tyrosine...