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Structure-function studies of an IGF-I analogue that can be chemically cleaved to a two-chain mini-IGF-I

Structure-function studies of an IGF-I analogue that can be chemically cleaved to a two-chain mini-IGF-I
Structure-function studies of an IGF-I analogue that can be chemically cleaved to a two-chain mini-IGF-I
The structure and biological activities of two disulphide isomers of a C-region deletion mutant of insulin-like growth factor-I (IGF-I) which has an Asn–Gly link engineered at the junction of the A- and B-regions were studied before and after chemical cleavage. Circular dichroism (CD) spectra and binding affinity to IGF binding protein 3 (IGFBP3) indicated that the treatment with hydroxylamine did not disrupt the overall tertiary fold of the hormones. Cleavage restored some binding affinity for the IGF-I receptor in both isomers and weakly restored the ability to stimulate incorporation of tritiated thymidine into DNA in NIH 3T3 fibroblasts transfected with the human IGF-I receptor. Cleavage also restored metabolic capacity, as measured by the ability of the isomers to promote lipogenesis in isolated rat adipocytes through the insulin receptor. These results are consistent with the theory that binding of IGF-I to the IGF-I receptor requires a conformational change similar to that involved in insulin binding the insulin receptor. The weak affinity for the IGF-I receptor after cleavage is consistent with the belief that residues in the C-region interact with the IGF-I receptor. This structural difference between insulin and IGF-I gives each a higher binding affinity for its own receptor.
0269-2139
61-65
Geddes, S.
4b3b6259-1f86-4280-afc1-a688a3598a5b
Holst, P.
abefe3d1-65a7-42a2-a82e-9705c54652b1
Grotzinger, J.
ac82c30b-0010-46a8-b5f4-c0911b800d34
Gill, R.
95656ecb-604f-425e-ac66-7dd36e47d94d
Nugent, P.
0b012273-c3a5-4319-ac63-d0d3e15f8f61
Meyts, P.
ea8fcb3c-aa62-4da5-8242-6562b692dbb4
Wollmer, A.
5fad9e94-568a-4b37-889e-7a9f573bc7ba
Wood, S.
c6b0bfe1-a0bc-4e57-84dd-60a8f936dae8
Pitts, J.
f3449a27-946c-4822-9936-9cd17d69c236
Geddes, S.
4b3b6259-1f86-4280-afc1-a688a3598a5b
Holst, P.
abefe3d1-65a7-42a2-a82e-9705c54652b1
Grotzinger, J.
ac82c30b-0010-46a8-b5f4-c0911b800d34
Gill, R.
95656ecb-604f-425e-ac66-7dd36e47d94d
Nugent, P.
0b012273-c3a5-4319-ac63-d0d3e15f8f61
Meyts, P.
ea8fcb3c-aa62-4da5-8242-6562b692dbb4
Wollmer, A.
5fad9e94-568a-4b37-889e-7a9f573bc7ba
Wood, S.
c6b0bfe1-a0bc-4e57-84dd-60a8f936dae8
Pitts, J.
f3449a27-946c-4822-9936-9cd17d69c236

Geddes, S., Holst, P., Grotzinger, J., Gill, R., Nugent, P., Meyts, P., Wollmer, A., Wood, S. and Pitts, J. (2001) Structure-function studies of an IGF-I analogue that can be chemically cleaved to a two-chain mini-IGF-I. Protein Engineering, 14 (1), 61-65.

Record type: Article

Abstract

The structure and biological activities of two disulphide isomers of a C-region deletion mutant of insulin-like growth factor-I (IGF-I) which has an Asn–Gly link engineered at the junction of the A- and B-regions were studied before and after chemical cleavage. Circular dichroism (CD) spectra and binding affinity to IGF binding protein 3 (IGFBP3) indicated that the treatment with hydroxylamine did not disrupt the overall tertiary fold of the hormones. Cleavage restored some binding affinity for the IGF-I receptor in both isomers and weakly restored the ability to stimulate incorporation of tritiated thymidine into DNA in NIH 3T3 fibroblasts transfected with the human IGF-I receptor. Cleavage also restored metabolic capacity, as measured by the ability of the isomers to promote lipogenesis in isolated rat adipocytes through the insulin receptor. These results are consistent with the theory that binding of IGF-I to the IGF-I receptor requires a conformational change similar to that involved in insulin binding the insulin receptor. The weak affinity for the IGF-I receptor after cleavage is consistent with the belief that residues in the C-region interact with the IGF-I receptor. This structural difference between insulin and IGF-I gives each a higher binding affinity for its own receptor.

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Published date: January 2001

Identifiers

Local EPrints ID: 56505
URI: http://eprints.soton.ac.uk/id/eprint/56505
ISSN: 0269-2139
PURE UUID: 0799286e-f022-46d3-96de-2534accfa6d7

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Date deposited: 08 Aug 2008
Last modified: 08 Jan 2022 10:05

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Contributors

Author: S. Geddes
Author: P. Holst
Author: J. Grotzinger
Author: R. Gill
Author: P. Nugent
Author: P. Meyts
Author: A. Wollmer
Author: S. Wood
Author: J. Pitts

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