Document Detail


Isoelectric points and post-translational modifications of connexin26 and connexin32.
MedLine Citation:
PMID:  16645047     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The isoelectric points of the gap junction proteins connexin26 (Cx26) and connexin32 (Cx32) were determined by isoelectric focusing in free fluids. The isoelectric points were significantly more acidic than predicted from amino acid sequences and different from each other, allowing homomeric channels to be resolved separately. The isoelectric points of the homomeric channels bracketed the isoelectric points of heteromeric Cx26/Cx32 channels. For heteromeric channels, Cx26 and Cx32 were found in overlapping, pH-focused fractions, indicating quaternary structure was retained. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was used to identify post-translational modifications of Cx26 and Cx32 cytoplasmic domains, including the first reported post-translational modifications of Cx26. Suspected modifications were hydroxylation and/or phosphorylation near the amino terminus of both connexins, gamma-carboxyglutamate residues in the cytoplasmic loop of both connexins, phosphorylation in the carboxyl-terminal domain of Cx32, and palmitoylation at the carboxyl-terminus of Cx32. These modifications contribute to the measured acidic isoelectric points of Cx26 and Cx32, whereas their low molecular masses would not appreciably change connexin SDS-PAGE mobility. Most of these modifications have not previously been identified for connexins and may be instrumental in guiding and understanding novel aspects of channel trafficking and molecular mechanisms of channel regulation.
Authors:
Darren Locke; Irina V Koreen; Andrew L Harris
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2006-04-27
Journal Detail:
Title:  FASEB journal : official publication of the Federation of American Societies for Experimental Biology     Volume:  20     ISSN:  1530-6860     ISO Abbreviation:  FASEB J.     Publication Date:  2006 Jun 
Date Detail:
Created Date:  2006-06-13     Completed Date:  2006-07-19     Revised Date:  2012-02-15    
Medline Journal Info:
Nlm Unique ID:  8804484     Medline TA:  FASEB J     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1221-3     Citation Subset:  IM    
Affiliation:
Department of Pharmacology and Physiology, New Jersey Medical School, 185 South Orange Ave., University of Medicine and Dentistry of New Jersey, Newark, New Jersey 07103, USA. lockeda@umdnj.edu
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MeSH Terms
Descriptor/Qualifier:
Animals
Connexins / chemistry*,  metabolism*
HeLa Cells
Humans
Isoelectric Focusing
Isoelectric Point
Mice
Protein Processing, Post-Translational
Rats
Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
Grant Support
ID/Acronym/Agency:
GM36044/GM/NIGMS NIH HHS; GM61406/GM/NIGMS NIH HHS
Chemical
Reg. No./Substance:
0/Connexins; 0/connexin 32; 127120-53-0/connexin 26

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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