The 47-kD lens-specific protein phakinin is a tailless intermediate filament protein and an assembly partner of filensin

dc.contributor.authorMerdes, A.en
dc.contributor.authorGounari, F.en
dc.contributor.authorGeorgatos, S. D.en
dc.date.accessioned2015-11-24T19:42:39Z
dc.date.available2015-11-24T19:42:39Z
dc.identifier.issn0021-9525-
dc.identifier.urihttps://olympias.lib.uoi.gr/jspui/handle/123456789/24673
dc.rightsDefault Licence-
dc.subjectAmino Acid Sequenceen
dc.subjectAnimalsen
dc.subjectBase Sequenceen
dc.subjectCattleen
dc.subjectCloning, Molecularen
dc.subjectConsensus Sequenceen
dc.subjectDNA, Complementary/geneticsen
dc.subjectEye Proteins/*chemistry/genetics/*metabolismen
dc.subjectFluorescent Antibody Techniqueen
dc.subjectIntermediate Filament Proteins/*chemistry/genetics/metabolismen
dc.subjectKeratins/metabolismen
dc.subjectLens, Crystalline/*chemistry/ultrastructureen
dc.subjectMacromolecular Substancesen
dc.subjectMolecular Sequence Dataen
dc.subjectProtein Bindingen
dc.subjectProtein Structure, Secondaryen
dc.subjectSequence Alignmenten
dc.subjectSequence Homology, Amino Aciden
dc.titleThe 47-kD lens-specific protein phakinin is a tailless intermediate filament protein and an assembly partner of filensinen
heal.abstractIn previous studies we have characterized a lens-specific intermediate filament (IF) protein, termed filensin. Filensin does not self-assemble into regular IFs but is known to associate with another 47-kD lens-specific protein which has been suggested to represent its assembly partner. To address this possibility, we cloned and sequenced the cDNA coding for the bovine 47-kD protein which we have termed phakinin (from the greek phi alpha kappa omicron sigma = phakos = lens). The predicted sequence comprises 406 amino acids and shows significant similarity (31.3% identity over 358 residues) to type I cytokeratins. Phakinin possesses a 95-residue, non-helical domain (head) and a 311 amino acid long alpha-helical domain punctuated with heptad repeats (rod). Similar to cytokeratin 19, phakinin lacks a COOH-terminal tail domain and it therefore represents the second known example of a naturally tailless IF protein. Confocal microscopy on frozen lens sections reveals that phakinin colocalizes with filensin and is distributed along the periphery of the lens fiber cells. Quantitative immunoblotting with whole lens fiber cell preparations and fractions of washed lens membranes suggest that the natural stoichiometry of phakinin to filensin is approximately 3:1. Under in vitro conditions, phakinin self-assembles into metastable filamentous structures which tend to aggregate into thick bundles. However, mixing of phakinin and filensin at an optimal ratio of 3:1 yields stable 10-nm filaments which have a smooth surface and are ultrastructurally indistinguishable from "mainstream" IFs. Immunolabeling with specific antibodies shows that these filaments represent phakinin/filensin heteropolymers. Despite its homology to the cytokeratins, phakinin does not coassemble with acidic (type I), or basic (type II) cytokeratins. From these data we conclude that filensin and phakinin are obligate heteropolymers which constitute a new membrane-associated, lens-specific filament system related to, but distinct from the known classes of IFs.en
heal.accesscampus-
heal.fullTextAvailabilityTRUE-
heal.identifier.secondaryhttp://www.ncbi.nlm.nih.gov/pubmed/7504675-
heal.journalNameJ Cell Biolen
heal.journalTypepeer-reviewed-
heal.languageen-
heal.publicationDate1993-
heal.recordProviderΠανεπιστήμιο Ιωαννίνων. Σχολή Επιστημών Υγείας. Τμήμα Ιατρικήςel
heal.typejournalArticle-
heal.type.elΆρθρο Περιοδικούel
heal.type.enJournal articleen

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