Insulin-like growth factor I receptors in retinal rod outer segments.

Y. Zick, Allen M. Spiegel, R. Sagi-Eisenberg

Research output: Contribution to journalArticle

43 Citations (Scopus)

Abstract

We have previously reported that the GDP-bound alpha-subunit of the GTP-binding protein transducin, present in outer segments of retinal rod cells (ROS), serves as a high affinity in vitro substrate (Km = 1 microM) for the insulin receptor kinase. The present study demonstrates that transducin also serves as in vitro substrate for an endogenous IGF-I receptor kinase isolated from ROS membranes. The presence of insulin-like growth factor I (IGF-I) receptors in ROS is evident from the high affinity and specific binding of 125I-IGF-I to ROS membranes (Kd = 3 nM) which contain 110 fmol of IGF-I binding sites/mg of membrane protein. Furthermore, cross-linking of 125I-IGF-I labels the 135-kDa alpha-subunit of this receptor. 125I-Insulin binding capacity to ROS membranes is less than 5% that of IGF-I. The IGF-I-stimulated tyrosine kinase activity in solubilized and partially purified receptors from ROS autophosphorylates its own 95-kDa beta-subunits as well as other substrates like transducin. Insulin, which is 200-fold less potent than IGF-I in competing for 125I-IGF-I binding, is only 5-fold less potent than IGF-I in stimulating the receptor kinase activity. This suggests that insulin is much more potent than IGF-I in coupling ligand binding with kinase activation. The previously reported presence of IGF-I in the vitreous, together with our present studies, strongly suggest that the IGF-I receptor kinase, through phosphorylation of endogenous proteins like transducin, could play a role in mediating transmembrane signal transduction in ROS.

Original languageEnglish (US)
Pages (from-to)10259-10264
Number of pages6
JournalJournal of Biological Chemistry
Volume262
Issue number21
StatePublished - Jul 25 1987
Externally publishedYes

Fingerprint

Retinal Photoreceptor Cell Outer Segment
Rod Cell Outer Segment
Retinal Rod Photoreceptor Cells
IGF Type 1 Receptor
Insulin-Like Growth Factor I
Transducin
Phosphotransferases
Cell membranes
Cell Membrane
Insulin
Substrates
GTP-Binding Protein alpha Subunits
Signal transduction
Phosphorylation
Insulin Receptor
Protein-Tyrosine Kinases
Labels
Signal Transduction
Membrane Proteins

ASJC Scopus subject areas

  • Biochemistry

Cite this

Insulin-like growth factor I receptors in retinal rod outer segments. / Zick, Y.; Spiegel, Allen M.; Sagi-Eisenberg, R.

In: Journal of Biological Chemistry, Vol. 262, No. 21, 25.07.1987, p. 10259-10264.

Research output: Contribution to journalArticle

Zick, Y. ; Spiegel, Allen M. ; Sagi-Eisenberg, R. / Insulin-like growth factor I receptors in retinal rod outer segments. In: Journal of Biological Chemistry. 1987 ; Vol. 262, No. 21. pp. 10259-10264.
@article{cc8bfbed56d64276bb7e2429f7ec4206,
title = "Insulin-like growth factor I receptors in retinal rod outer segments.",
abstract = "We have previously reported that the GDP-bound alpha-subunit of the GTP-binding protein transducin, present in outer segments of retinal rod cells (ROS), serves as a high affinity in vitro substrate (Km = 1 microM) for the insulin receptor kinase. The present study demonstrates that transducin also serves as in vitro substrate for an endogenous IGF-I receptor kinase isolated from ROS membranes. The presence of insulin-like growth factor I (IGF-I) receptors in ROS is evident from the high affinity and specific binding of 125I-IGF-I to ROS membranes (Kd = 3 nM) which contain 110 fmol of IGF-I binding sites/mg of membrane protein. Furthermore, cross-linking of 125I-IGF-I labels the 135-kDa alpha-subunit of this receptor. 125I-Insulin binding capacity to ROS membranes is less than 5{\%} that of IGF-I. The IGF-I-stimulated tyrosine kinase activity in solubilized and partially purified receptors from ROS autophosphorylates its own 95-kDa beta-subunits as well as other substrates like transducin. Insulin, which is 200-fold less potent than IGF-I in competing for 125I-IGF-I binding, is only 5-fold less potent than IGF-I in stimulating the receptor kinase activity. This suggests that insulin is much more potent than IGF-I in coupling ligand binding with kinase activation. The previously reported presence of IGF-I in the vitreous, together with our present studies, strongly suggest that the IGF-I receptor kinase, through phosphorylation of endogenous proteins like transducin, could play a role in mediating transmembrane signal transduction in ROS.",
author = "Y. Zick and Spiegel, {Allen M.} and R. Sagi-Eisenberg",
year = "1987",
month = "7",
day = "25",
language = "English (US)",
volume = "262",
pages = "10259--10264",
journal = "Journal of Biological Chemistry",
issn = "0021-9258",
publisher = "American Society for Biochemistry and Molecular Biology Inc.",
number = "21",

}

TY - JOUR

T1 - Insulin-like growth factor I receptors in retinal rod outer segments.

AU - Zick, Y.

AU - Spiegel, Allen M.

AU - Sagi-Eisenberg, R.

PY - 1987/7/25

Y1 - 1987/7/25

N2 - We have previously reported that the GDP-bound alpha-subunit of the GTP-binding protein transducin, present in outer segments of retinal rod cells (ROS), serves as a high affinity in vitro substrate (Km = 1 microM) for the insulin receptor kinase. The present study demonstrates that transducin also serves as in vitro substrate for an endogenous IGF-I receptor kinase isolated from ROS membranes. The presence of insulin-like growth factor I (IGF-I) receptors in ROS is evident from the high affinity and specific binding of 125I-IGF-I to ROS membranes (Kd = 3 nM) which contain 110 fmol of IGF-I binding sites/mg of membrane protein. Furthermore, cross-linking of 125I-IGF-I labels the 135-kDa alpha-subunit of this receptor. 125I-Insulin binding capacity to ROS membranes is less than 5% that of IGF-I. The IGF-I-stimulated tyrosine kinase activity in solubilized and partially purified receptors from ROS autophosphorylates its own 95-kDa beta-subunits as well as other substrates like transducin. Insulin, which is 200-fold less potent than IGF-I in competing for 125I-IGF-I binding, is only 5-fold less potent than IGF-I in stimulating the receptor kinase activity. This suggests that insulin is much more potent than IGF-I in coupling ligand binding with kinase activation. The previously reported presence of IGF-I in the vitreous, together with our present studies, strongly suggest that the IGF-I receptor kinase, through phosphorylation of endogenous proteins like transducin, could play a role in mediating transmembrane signal transduction in ROS.

AB - We have previously reported that the GDP-bound alpha-subunit of the GTP-binding protein transducin, present in outer segments of retinal rod cells (ROS), serves as a high affinity in vitro substrate (Km = 1 microM) for the insulin receptor kinase. The present study demonstrates that transducin also serves as in vitro substrate for an endogenous IGF-I receptor kinase isolated from ROS membranes. The presence of insulin-like growth factor I (IGF-I) receptors in ROS is evident from the high affinity and specific binding of 125I-IGF-I to ROS membranes (Kd = 3 nM) which contain 110 fmol of IGF-I binding sites/mg of membrane protein. Furthermore, cross-linking of 125I-IGF-I labels the 135-kDa alpha-subunit of this receptor. 125I-Insulin binding capacity to ROS membranes is less than 5% that of IGF-I. The IGF-I-stimulated tyrosine kinase activity in solubilized and partially purified receptors from ROS autophosphorylates its own 95-kDa beta-subunits as well as other substrates like transducin. Insulin, which is 200-fold less potent than IGF-I in competing for 125I-IGF-I binding, is only 5-fold less potent than IGF-I in stimulating the receptor kinase activity. This suggests that insulin is much more potent than IGF-I in coupling ligand binding with kinase activation. The previously reported presence of IGF-I in the vitreous, together with our present studies, strongly suggest that the IGF-I receptor kinase, through phosphorylation of endogenous proteins like transducin, could play a role in mediating transmembrane signal transduction in ROS.

UR - http://www.scopus.com/inward/record.url?scp=0023664702&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0023664702&partnerID=8YFLogxK

M3 - Article

VL - 262

SP - 10259

EP - 10264

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 21

ER -