Endocrinology, Vol 134, 848-852, Copyright © 1994 by Endocrine Society

ARTICLES

Purification and characterization of the acid-labile subunit of rat serum insulin-like growth factor binding protein complex

RC Baxter and J Dai
Department of Endocrinology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia.

Circulating insulin-like growth factor (IGF) binding protein-3 (IGFBP- 3), when occupied by IGF-I or IGF-II, combines with an acid-labile glycoprotein subunit (ALS) to form a high molecular weight complex. In this study, ALS from rat serum has been purified and its properties investigated. Purification involved ion-exchange chromatography, and affinity chromatography on an IGF-I-IGFBP-3 column, yielding almost 1 mg ALS from 100 ml serum. Amino-terminal sequencing confirmed the prediction from previous complementary DNA analysis but indicated that the protein may circulate in a truncated form. Rat ALS was almost as potent as human ALS in binding to human IGF-I-IGFBP-3 complex (association constant, 2.3 nM-1). A sensitive RIA was developed, with high specificity for rodent ALS. Serum ALS rose from 3 micrograms/ml in 2-day-old rats to more than 40 micrograms/ml at 10 weeks, with no sex difference. GH-deficient rats showed 60-75% lower values than controls. This study shows rat ALS to have similar binding properties, and age and GH dependence, to human ALS. The new RIA will facilitate studies of IGF and IGFBP regulation in the rat.

This article has been cited by other articles:

				J. W Kim, R. P Rhoads, N. Segoale, N. B Kristensen, D. E Bauman, and Y. R Boisclair Isolation of the cDNA encoding the acid labile subunit (ALS) of the 150 kDa IGF-binding protein complex in cattle and ALS regulation during the transition from pregnancy to lactation. J. Endocrinol., June 1, 2006; 189(3): 583 - 593. [Abstract] [Full Text] [PDF]

				S.-E. Kong, R. C. Baxter, and P. J. D. Delhanty Age-Dependent Regulation of the Acid-Labile Subunit in Response to Fasting-Refeeding in Rats Endocrinology, December 1, 2002; 143(12): 4505 - 4512. [Abstract] [Full Text] [PDF]

				M. Cisternino, M. Draghi, S. Lauriola, D. Scarcella, S. Bernasconi, L. Cavallo, F. De Luca, A. Lomeo, and L. Tato The Acid-Labile Subunit of Human Ternary Insulin-Like Growth Factor-Binding Protein Complex in Girls with Central Precocious Puberty before and during Gonadotropin-Releasing Hormone Analog Therapy J. Clin. Endocrinol. Metab., October 1, 2002; 87(10): 4629 - 4633. [Abstract] [Full Text] [PDF]

				S.-E. Kong, S. M. Firth, R. C. Baxter, and P. J. D. Delhanty Regulation of the acid-labile subunit in sustained endotoxemia Am J Physiol Endocrinol Metab, October 1, 2002; 283(4): E692 - E701. [Abstract] [Full Text] [PDF]

				J. V. Silha, Y. Gui, T. Modric, A. Suwanichkul, S. K. Durham, D. R. Powell, and L. J. Murphy Overexpression of the Acid-Labile Subunit of the IGF Ternary Complex in Transgenic Mice Endocrinology, October 1, 2001; 142(10): 4305 - 4313. [Abstract] [Full Text] [PDF]

				P. J. D. Delhanty, C. D. Scott, S. Babu, and R. C. Baxter Acid-labile subunit regulation during the early stages of liver regeneration: implications for glucoregulation Am J Physiol Endocrinol Metab, February 1, 2001; 280(2): E287 - E295. [Abstract] [Full Text] [PDF]

				R. P. Rhoads, P. L. Greenwood, A. W. Bell, and Y. R. Boisclair Organization and Regulation of the Gene Encoding the Sheep Acid-Labile Subunit of the 150-Kilodalton Insulin-Like Growth Factor-Binding Protein Complex Endocrinology, April 1, 2000; 141(4): 1425 - 1433. [Abstract] [Full Text] [PDF]

				A. Suwanichkul, Y. R. Boisclair, R. C. Olney, S. K. Durham, and D. R. Powell Conservation of a Growth Hormone-Responsive Promoter Element in the Human and Mouse Acid-Labile Subunit Genes Endocrinology, February 1, 2000; 141(2): 833 - 838. [Abstract] [Full Text] [PDF]

				J. Frystyk, P. J. D. Delhanty, C. Skjarbak, and R. C. Baxter Changes in the circulating IGF system during short-term fasting and refeeding in rats Am J Physiol Endocrinol Metab, August 1, 1999; 277(2): E245 - E252. [Abstract] [Full Text] [PDF]

				A. J. Kee, R. C. Baxter, A. R. Carlsson, and R. C. Smith Parenteral amino acid intake alters the anabolic actions of insulin-like growth factor I in rats Am J Physiol Endocrinol Metab, July 1, 1999; 277(1): E63 - E72. [Abstract] [Full Text] [PDF]

				J. Frystyk, H. Gronbak, C. Skjarbak, A. Flyvbjerg, H. Orskov, and R. C. Baxter Developmental Changes in Serum Levels of Free and Total Insulin-Like Growth Factor I (IGF-I), IGF-Binding Protein-1 and -3, and the Acid-Labile Subunit in Rats Endocrinology, October 1, 1998; 139(10): 4286 - 4292. [Abstract] [Full Text] [PDF]

				G. T. Ooi, K. R. Hurst, M. N. Poy, M. M. Rechler, and Y. R. Boisclair Binding of STAT5a and STAT5b to a Single Element Resembling a {gamma}-Interferon-Activated Sequence Mediates the Growth Hormone Induction of the Mouse Acid-Labile Subunit Promoter in Liver Cells Mol. Endocrinol., May 1, 1998; 12(5): 675 - 687. [Abstract] [Full Text]

				R. Hashimoto, M. Ono, H. Fujiwara, N. Higashihashi, M. Yoshida, T. Enjoh-Kimura, and K.-i. Sakano Binding Sites and Binding Properties of Binary and Ternary Complexes of Insulin-like Growth Factor-II (IGF-II), IGF-binding Protein-3, and Acid-labile Subunit J. Biol. Chem., October 31, 1997; 272(44): 27936 - 27942. [Abstract] [Full Text] [PDF]

				I. Ueki, G. T. Ooi, M. L. Tremblay, K. R. Hurst, L. A. Bach, and Y. R. Boisclair Inactivation of the acid labile subunit gene in mice results in mild retardation of postnatal growth despite profound disruptions in the circulating insulin-like growth factor system PNAS, June 6, 2000; 97(12): 6868 - 6873. [Abstract] [Full Text] [PDF]