title: The lipidation profile of aquaporin-0 correlates with the acyl composition of phosphoethanolamine lipids in lens membranes.
abstract: The lens fiber major intrinsic protein (otherwise known as aquaporin-0 (AQP0), MIP26 and MP26) has been examined by mass spectrometry (MS) in order to determine the speciation of acyl modifications to the side chains of lysine residues and the N-terminal amino group. The speciation of acyl modifications to the side chain of one specific, highly conserved lysine residue (K238) and the N-terminal amino group of human and bovine AQP0 revealed, in decreasing order of abundance, oleoyl, palmitoyl, stearoyl, eicosenoyl, dihomo-γ-linolenoyl, palmitoleoyl and eicosadienoyl modifications. In the case of human AQP0, an arachidonoyl modification was also found at the N-terminus. The relative abundances of these modifications mirror the fatty acid composition of lens phosphatidylethanolamine lipids. This lipid class would be expected to be concentrated in the inner leaflet of the lens fiber membrane to which each of the potential AQP0 lipidation sites is proximal. Our data evidence a broad lipidation profile that is both species and site independent, suggesting a chemical-based ester aminolysis mechanism to explain such modifications.
authors.affiliation: Chemistry Department, Durham University, Durham DH1 3LE, UK; Department of Biology, Faculty of Science, Soran University, Soran, Kurdistan Regional Government, Iraq.
authors.forename: Vian S
authors.initials: VS
authors.lastname: Ismail
authors.affiliation: Chemistry Department, Durham University, Durham DH1 3LE, UK.
authors.forename: Jackie A
authors.initials: JA
authors.lastname: Mosely
authors.affiliation: Biophysical Sciences Institute, Durham University, Durham DH1 3LE, UK.
authors.forename: Antal
authors.initials: A
authors.lastname: Tapodi
authors.affiliation: School of Biological Sciences, Durham University, Durham DH1 3LE, UK; Biophysical Sciences Institute, Durham University, Durham DH1 3LE, UK. Electronic address: r.a.quinlan@durham.ac.uk.
authors.forename: Roy A
authors.initials: RA
authors.lastname: Quinlan
authors.affiliation: Chemistry Department, Durham University, Durham DH1 3LE, UK; Biophysical Sciences Institute, Durham University, Durham DH1 3LE, UK. Electronic address: j.m.sanderson@durham.ac.uk.
authors.forename: John M
authors.initials: JM
authors.lastname: Sanderson
mesh_terms: D000818:Animals; D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D001095:Arachidonic Acids / Q000378:metabolism*; D002417:Cattle; D004983:Ethanolamines / Q000737:chemistry / Q000378:metabolism*; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D007908:Lens, Crystalline / Q000737:chemistry / Q000378:metabolism*; D054878:Lipoylation; D008566:Membranes; D011499:Protein Processing, Post-Translational; D055815:Young Adult
chemical_list: D020346:Aquaporins; D001095:Arachidonic Acids; D004983:Ethanolamines; D005136:Eye Proteins; C030328:aquaporin 0; C005448:phosphorylethanolamine
keywords: Aquaporin; Lipid; Lipidation; Membrane; Membrane protein; Posttranslational modification