title: The pentameric channel of COMPcc in complex with different fatty acids.
abstract: BACKGROUND
  COMPcc forms a pentameric left-handed coiled coil that is known to bind hydrophilic signaling molecules such as vitamin D(3), and vitamin A.
  
  
  RESULTS
  In an integrated approach we reveal the unique binding properties of COMPcc for saturated and unsaturated fatty acids. Our observations suggest that residues Met33 (gating pore), Thr40/Asn41 (water chamber) and Gln54 (electrostatic trap) are key elements for the binding of fatty acids by COMPcc. In addition, this work characterizes the binding of various fatty acids to COMPcc using fluorescence spectroscopy. Our findings reveal a binding trend within the hydrophobic channel of COMPcc, namely, that is driven by length of the methylene tail and incorporation of unsaturation.
  
  
  CONCLUSIONS
  The unique binding properties imply that COMPcc may be involved in signalling functions in which hydrophilic ligands are involved. The pentameric channel is a unique carrier for lipophilic compounds. This opens the exciting possibility that COMPcc could be developed as a targeted drug delivery system.
authors.affiliation: Department of Chemistry, University of Manitoba, Canada.
authors.forename: Ainsley
authors.initials: A
authors.lastname: McFarlane
authors.forename: Ainsley A
authors.initials: AA
authors.lastname: MacFarlane
authors.forename: George
authors.initials: G
authors.lastname: Orriss
authors.forename: Natalie
authors.initials: N
authors.lastname: Okun
authors.forename: Markus
authors.initials: M
authors.lastname: Meier
authors.forename: Thomas
authors.initials: T
authors.lastname: Klonisch
authors.forename: Mazdak
authors.initials: M
authors.lastname: Khajehpour
authors.forename: Jörg
authors.initials: J
authors.lastname: Stetefeld
mesh_terms: D064236:Cartilage Oligomeric Matrix Protein; D002762:Cholecalciferol / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000737:chemistry; D005227:Fatty Acids / Q000737:chemistry*; D006023:Glycoproteins / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D008024:Ligands; D064235:Matrilin Proteins; D008968:Molecular Conformation; D019308:Palmitic Acid / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D015398:Signal Transduction; D012997:Solvents / Q000737:chemistry; D013050:Spectrometry, Fluorescence / Q000379:methods; D014801:Vitamin A / Q000378:metabolism
chemical_list: D064236:Cartilage Oligomeric Matrix Protein; D016326:Extracellular Matrix Proteins; D005227:Fatty Acids; D006023:Glycoproteins; D008024:Ligands; D064235:Matrilin Proteins; D012997:Solvents; C577553:TSP5 protein, human; D014801:Vitamin A; D002762:Cholecalciferol; D019308:Palmitic Acid