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2ifi

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{{STRUCTURE_2ifi| PDB=2ifi | SCENE= }}
{{STRUCTURE_2ifi| PDB=2ifi | SCENE= }}
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'''Ala6 Variant of ImI Conotoxin'''
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===Ala6 Variant of ImI Conotoxin===
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==Overview==
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Alpha-conotoxins isolated from Conus venoms contain 11-19 residues and preferentially fold into the globular conformation that possesses a specific disulfide pairing pattern (C1-3, C2-4). We and others isolated a new family of chi-conotoxins (also called lambda conotoxins) with the conserved cysteine framework of alpha-conotoxins but with alternative disulfide pairing (C1-4, C2-3) resulting in the ribbon conformation. In both families, disulfide pairing and hence folding are important for their biological potency. By comparing the structural differences, we identified potential structural determinants responsible for the folding tendencies of these conotoxins. We examined the role of conserved proline in the first intercysteine loop and the conserved C-terminal amide on folding patterns of synthetic analogues of ImI conotoxin by comparing the isoforms with the regiospecifically synthesized conformers. Deamidation at the C-terminus and substitution of proline in the first intercysteine loop switch the folding pattern from the globular form of alpha-conotoxins to the ribbon form of chi/lambda-conotoxins. The findings are corroborated by reciprocal folding of CMrVIA chi/lambda-conotoxins. Substitution of Lys-6 from the first intercysteine loop of CMrVIA conotoxin with proline, as well as the inclusion of an amidated C-terminal shifted the folding preference of CMrVIA conotoxin from its native ribbon conformation toward the globular conformation. Binding assays of ImI conotoxin analogues with Aplysia and Bulinus acetylcholine binding protein indicate that both these substitutions and their consequent conformational change substantially impact the binding affinity of ImI conotoxin. These results strongly indicate that the first intercysteine loop proline and C-terminal amidation act as conformational switches in alpha- and chi/lambda-conotoxins.
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(as it appears on PubMed at http://www.pubmed.gov), where 17315952 is the PubMed ID number.
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{{ABSTRACT_PUBMED_17315952}}
==About this Structure==
==About this Structure==
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Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2IFI OCA].
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Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2IFI OCA].
==Reference==
==Reference==
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[[Category: Disulfide linkage]]
[[Category: Disulfide linkage]]
[[Category: Ribbon conformation]]
[[Category: Ribbon conformation]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 07:26:52 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 10:51:41 2008''

Revision as of 07:51, 29 July 2008

Image:2ifi.png

Template:STRUCTURE 2ifi

Ala6 Variant of ImI Conotoxin

Template:ABSTRACT PUBMED 17315952

About this Structure

Full experimental information is available from OCA.

Reference

Protein folding determinants: structural features determining alternative disulfide pairing in alpha- and chi/lambda-conotoxins., Kang TS, Radic Z, Talley TT, Jois SD, Taylor P, Kini RM, Biochemistry. 2007 Mar 20;46(11):3338-55. Epub 2007 Feb 22. PMID:17315952

Page seeded by OCA on Tue Jul 29 10:51:41 2008

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