title: Alcohol binding in the C1 (C1A+C1B) domain of protein kinase C epsilon.
abstract: BACKGROUND
  Alcohol regulates the expression and function of protein kinase C epsilon (PKCε). In a previous study we identified an alcohol binding site in the C1B, one of the twin C1 subdomains of PKCε (Das et al., Biochem. J., 421, 405-13, 2009).
  
  
  METHODS
  In this study, we investigated alcohol binding in the entire C1 domain (combined C1A and C1B) of PKCε. Fluorescent phorbol ester, SAPD and fluorescent diacylglycerol (DAG) analog, dansyl-DAG were used to study the effect of ethanol, butanol, and octanol on the ligand binding using fluorescence resonance energy transfer (FRET). To identify alcohol binding site(s), PKCεC1 was photolabeled with 3-azibutanol and 3-azioctanol, and analyzed by mass spectrometry. The effects of alcohols and the azialcohols on PKCε were studied in NG108-15 cells.
  
  
  RESULTS
  In the presence of alcohol, SAPD and dansyl-DAG showed different extent of FRET, indicating differential effects of alcohol on the C1A and C1B subdomains. Effects of alcohols and azialcohols on PKCε in NG108-15 cells were comparable. Azialcohols labeled Tyr-176 of C1A and Tyr-250 of C1B. Inspection of the model structure of PKCεC1 reveals that these residues are 40Å apart from each other indicating that these residues form two different alcohol binding sites.
  
  
  CONCLUSIONS
  The present results provide evidence for the presence of multiple alcohol-binding sites on PKCε and underscore the importance of targeting this PKC isoform in developing alcohol antagonists.
authors.affiliation: Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX 77204, United States.
authors.forename: Satyabrata
authors.initials: S
authors.lastname: Pany
authors.affiliation: Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX 77204, United States. Electronic address: jdas@uh.edu.
authors.forename: Joydip
authors.initials: J
authors.lastname: Das
mesh_terms: D000438:Alcohols / Q000494:pharmacology*; D000595:Amino Acid Sequence; D001665:Binding Sites; D031541:Fluorescence Resonance Energy Transfer; D008969:Molecular Sequence Data; D051744:Protein Kinase C-epsilon / Q000737:chemistry*; D017434:Protein Structure, Tertiary
chemical_list: D000438:Alcohols; D051744:Protein Kinase C-epsilon
keywords: Alcohol-binding site; Alcoholism; Fluorescence resonance energy transfer (FRET); Mass spectrometry (MS); Photoaffinity; Protein kinase Cε (PKCε)