Comparison of receptors for insulin-like growth factor II from various rat tissues

ABSTRACT Receptors for insulin-like growth factor II (IGF-II) have been compared in solubilized microsomal membranes from rat lung, brain, kidney, heart, epididymal and subcutaneous fat, ovary, testis and adrenals. Highest binding/μg protein was seen with testicular membranes. Receptors from all tissues showed high affinity for human IGF-II (mean association constant = 65 litres/nmol) and a high degree of specificity (mean IGF-I cross-reactivity 0·3%; no cross-reactivity with insulin). Affinity labelling followed by sodium dodecyl sulphate polyacrylamide gel electrophoresis showed binding was only to a type-II IGF receptor, with a major band seen at a molecular weight of about 230 000 in lung, brain, kidney and testis, and 240 000 in heart, fat and adrenal gland. All tissues showed broad or bimodal pH dependence of binding, with optima seen at about pH 6 and pH 9. Mild stimulation of IGF-II binding by low calcium concentrations (1–2 mmol/l) was seen in all tissues, although higher concentrations were inhibitory in the brain. It was concluded that IGF-II receptors from different rat tissues, when studied under uniform conditions, show similar binding affinities but differences in size and regulation which might be missed if receptors are examined in separate studies. J. Endocr. (1987) 115, 35–41

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Developmental regulation of insulin-like growth factor II mRNA in different rat tissues.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)69282-8 ◽

1986 ◽

Vol 261 (28) ◽

pp. 13144-13150 ◽

Cited By ~ 7

Author(s):

A L Brown ◽

D E Graham ◽

S P Nissley ◽

D J Hill ◽

A J Strain ◽

...

Keyword(s):

Growth Factor ◽

Developmental Regulation ◽

Rat Tissues ◽

Insulin Like Growth Factor ◽

Factor Ii

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SECRETION OF SOLUBLE INSULIN-LIKE GROWTH FACTOR-II/MANNOSE 6-PHOSPHATE RECEPTOR BY RAT TISSUES IN CULTURE

Endocrinology ◽

10.1210/endo-128-4-2204 ◽

1991 ◽

Vol 128 (4) ◽

pp. 2204-2206 ◽

Cited By ~ 11

Author(s):

Gabriele Bobek ◽

Carolyn D. Scott ◽

Robert C. Baxter

Keyword(s):

Growth Factor ◽

Rat Tissues ◽

Insulin Like Growth Factor ◽

Factor Ii ◽

Soluble Insulin ◽

Mannose 6 Phosphate

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Processing of the insulin-like growth factor-IImannose 6-phosphate receptor in isolated liver subcellular fractions

Biochemistry and Cell Biology ◽

10.1139/o01-100 ◽

2001 ◽

Vol 79 (4) ◽

pp. 469-477

Author(s):

Khadija Tahiri ◽

Laurence Cam ◽

Bernard Desbuquois ◽

Geneviève Chauvet

Keyword(s):

Plasma Membrane ◽

Growth Factor ◽

Polyacrylamide Gel Electrophoresis ◽

Subcellular Fractions ◽

Soluble Form ◽

Dependent Manner ◽

Insulin Like Growth Factor ◽

Factor Ii ◽

Mannose 6 Phosphate ◽

Isolated Liver

A truncated, soluble form of the insulin-like growth factor-IImannose 6-phosphate (IGF-IIM6P) receptor has been identified in serum and shown to be released from cultured tissues and cells, liver being the main contributor to serum receptor in adult rats. In the present study, the processing of the IGF-IIM6P receptor has been characterized in isolated liver subcellular fractions using ligand binding, affinity crosslinking, and Western immunoblotting techniques. The receptor in plasma membrane fractions differed from that in Golgi-endosomal fractions by: (i) a lower molecular size upon reducing polyacrylamide gel electrophoresis (245 vs. 255 kDa); (ii) a less tight membrane association as judged upon extractibility by NaCl; and (iii) the inability to recognize antibody anti-22C, directed against the cytoplasmic domain of the receptor. Incubation of cell fractions at 30°C led to a pH- and time-dependent release of the receptor into the medium. The pH optimum for release was 5.5 in the Golgi-endosomal fraction and 7.5 in plasma membrane fractions; at this pH, approximately 2% and 20%30% of total receptors were released per hour, respectively. Receptor release was inhibited in a dose-dependent manner by aprotinin, benzamidine, and leupeptin in the Golgi-endosomal fraction, and by 1,10 phenanthroline in plasma membrane fractions, although high concentrations were required for inhibition. The receptor released from Golgi-endosomes showed a 510 kDa reduction in size and a loss of ability to recognize antibody anti-22C, but that released from plasma membranes showed little or no changes in size. We conclude that soluble, carboxy-terminally truncated forms of the IGF-IIM6P receptor are generated from the intact receptor in isolated Golgi-endosomal and plasma membrane fractions. However, receptor processing in these fractions exhibits different properties, suggesting the involvement of different proteases.Key words: insulin-like growth factor-IImannose 6-phosphate (IGF-IIM6P) receptor, liver, plasma membrane, Golgi apparatus, endosomes.

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Purification of a basic somatomedin, from human plasma Cohn fraction IV-1, with physicochemical and radioimmunoassay similarity to somatomedin-C and insulin-like growth factor

Canadian Journal of Biochemistry ◽

10.1139/o79-172 ◽

1979 ◽

Vol 57 (11) ◽

pp. 1289-1298 ◽

Cited By ~ 27

Author(s):

R. Marvin Bala ◽

B. Bhaumick

Keyword(s):

Growth Factor ◽

Human Plasma ◽

Protein Separation ◽

Polyacrylamide Gel Electrophoresis ◽

Sodium Dodecyl ◽

Extraction Procedure ◽

Molecular Size ◽

Protein Band ◽

Insulin Like Growth Factor ◽

Igf I

A basic somatomedin (SM) was purified from human plasma Cohn fraction IV-1 using an initial acid–ethanol–acetone extraction procedure followed by alternating molecular size or charge protein separation techniques. The final recovery of SM bioactivity was approximately 2% of that present in the starting Cohn fraction. The purified SM has an approximate molecular weight of 7500, pI 8.6, 4000 SM bioactivity units per milligram (as measured by a hypophysectomized rat bioassay) and a parallel approximately equipotent radioimmunoassay dose–response curve to SM-C and insulin-like growth factor-I (IGF-I). Sodium dodecyl sulfate – polyacrylamide gel electrophoresis of this purified SM revealed a single protein band. The preliminary determination of the amino acid sequence of the N terminus suggested that this SM preparation was over 75% pure and the first five N-terminal amino acids were identical with those of IGF-I.

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Chemistry, structure, and function of insulin-like growth factors and their receptors: a review

Canadian Journal of Biochemistry and Cell Biology ◽

10.1139/o84-158 ◽

1984 ◽

Vol 62 (11) ◽

pp. 1237-1245 ◽

Cited By ~ 24

Author(s):

James F. Perdue

Keyword(s):

Growth Factor ◽

Polyacrylamide Gel Electrophoresis ◽

Sodium Dodecyl ◽

Insulin Receptors ◽

Cross Reactivity ◽

Blood Levels ◽

Protein Kinase Activity ◽

Binding Studies ◽

Normal Children ◽

Igf I

Human serum contains two classes of somatomedins (Sin) with similar three-dimensional structures and mass (i.e., ~7500 kdaltons (kd)), but that can be distinguished from each other by their isoelectric point (pI) values. Those with alkaline pI's include the presumably identical molecules of insulin-like growth factor I (IGF-I), SmA, SmC, and basic Sm. In humans, the neutral–acidic class of Sm is represented by IGF-II. The sera of rats and other animals contain similar classes of Sm. In normal children and adults, plasma levels of both IGF-I and -II are under growth hormone control, although only elevated concentrations of the former can be positively correlated with adolescent skeletal growth. Elevated blood levels of IGF-II or an embryonic form of it, however, are correlated with fetal development of rats, sheep, and possibly in humans. As evidenced from competitive radioreceptor binding studies and affinity-labelling techniques, receptors that bind insulin and IGF-I are immunologically, structurally, and functionally related: (a) monoclonal and polyclonal antibodies to insulin receptors recognize determinants on receptors that bind IGF-I; (b) both receptors have 140-, 95-, and possibly 45-kd subunits that are interchain disulfide-bonded to form glycoprotein complexes of relative masses (Mr) 300 000 – 400 000; and (c) occupancy of the 140-kd subunits by hormone or growth factor stimulates the phosphorylation of tyrosine residues on the 95-kd subunit by receptor-associated protein kinases. Receptors that bind IGF-II are very different from insulin or IGF-I receptors: (a) there is no evidence of immunological cross-reactivity to the insulin receptors or of intrinsic protein kinase activity and (b) estimates of the molecular weight of the detergent-solubilized IGF-II receptor from its hydrodynamic properties or from its electrophoretic mobility during quantitative or sodium dodecyl sulfate–polyacrylamide gel electrophoresis established it to be a single-chained glycoprotein of MT 220 000 held together by intrachain disulfide bonds.

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High-affinity receptor for insulin-like growth factor II in rat liver: properties and regulation in vivo

Journal of Endocrinology ◽

10.1677/joe.0.1130027 ◽

1987 ◽

Vol 113 (1) ◽

pp. 27-35 ◽

Cited By ~ 4

Author(s):

J. M. Bryson ◽

R. C. Baxter

Keyword(s):

Growth Factor ◽

Rat Liver ◽

Cross Reactivity ◽

Female Rats ◽

Insulin Like Growth Factor ◽

High Affinity ◽

Factor Ii ◽

High Affinity Receptor ◽

Microsomal Membranes ◽

Affinity Receptor

ABSTRACT Receptors for insulin-like growth factor II (IGF-II) have been identified in many tissue types and have been shown to differ widely in their specificities and affinities. We have characterized the IGF-II receptor in rat liver microsomal membranes, both in the intact membrane and in a solubilized extract. Binding was time- and temperature-dependent and was unaffected by changes in pH in the range 6–9. Half-maximal displacement was obtained with 0·33 ng IGF-II/ml standard, and Scatchard analysis showed a class of receptors with an affinity for IGF-II of 1·33 ± 0·36 × 1010 litres/mol which increased threefold in the presence of Ca (1 mmol/l) to 3·74 ± 0·89 × 1010 litres/mol. There was also a threefold decrease in the rate of dissociation in the presence of Ca. Cross-reactivity with IGF-I was < 1% and there was no cross-reactivity with insulin. Infusion of rat GH or prolactin for 1 week, at the rate of 175–200 μg/day, into female rats had no effect on IGF-II binding in control animals, but rat GH infusion caused a 60% increase (P< 0·001) in binding in hypophysectomized rats by increasing the number of receptors. These studies demonstrate that rat liver microsomal membranes contain a highly specific, high-affinity receptor for IGF-II which may be under partial GH control J. Endocr. (1987) 113, 27–35

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