Type II insulin-like growth factor receptor is present in rat serum.

Abstract

We previously identified in fetal rat serum a component capable of specifically binding radiolabeled insulinlike growth factor type II (IGF-II) that is considerably larger than both the fetal (40 kDa) and the adult (150 kDa (19-days gestation) and in sera from 3-, 10-, and 20-day-old rats, the concentrations of receptor protein were similar (1-5 gug/ml). The level of the type II IGF receptor in serum declined dramatically between age 20 and 40 days, but the receptor was still measurable at age 12 mo. We conclude that the type H IGF receptor is present in rat serum and is developmentally regulated.The insulin-like growth factors (IGF-I and IGF-II), which show extensive amino acid sequence homology with insulin (1), are mitogens for cells in culture, frequently acting in concert with other growth factors (2). IGF-I mediates the anabolic action of pituitary growth hormone in vivo (3). The in vivo role for IGF-II is less clear, but the observation that IGF-II concentration is high in fetal rat serum, with a decline postnatally, has led to the proposal that IGF-II may be important for fetal growth in the rat (4, 5).IGF-I and IGF-II bind to high-affinity receptors present on many cells and tissues (6)

A Comparative Proteomic Analysis of Human and Rat Embryonic Cerebrospinal Fluid

“…A soluble form of the receptor has been found in the serum, amniotic fluid, and urine of both rodents and humans, affecting organ size based on its interaction with IGF2 and other factors. [39][40][41][42][43] Subcellular Localization. To compare the e-CSF of human and rat further, we analyzed the 188 proteins found in the human e-CSF and the 137 proteins in the rat e-CSF present in all samples based on subcellular localization, molecular function, and biological process.…”

The Effects of Altered Nutritional Status upon Insulin-Like Growth Factors and their Binding Proteins in Neonatal Rats

“…However, in the human and rat fetus, the predominant carrier protein species is a 35-40 kD rnol wt protein that is not under GH regulation and appears immunologically distinct from acid generated proteins from the adult 150 kD rnol wt species (28,29). A 250 kD rnol wt species has also been identified and, in the rat, may be identical to the type I1 IGF receptor (30). However, regulation of synthesis and release of this protein are not understood.…”

Aberrant imprinting of the insulin-like growth factor II receptor gene in Wilms' tumor

“…It is known that the mitogenic actions of IGF-II are transmitted by the type I IGF receptor (Kiess et al, 1987;Ellis et al, 1996), which binds both IGF-I and IGF-II and acts as a ligand-activated tyrosine kinase. By contrast, IGF2R encodes a 280 kDa membrane receptor with no known intracellular transduction mechanism, involved in the targeting of lysosomal enzymes to the lysosomes (reviewed by Polychronakos, 1989).…”