title: Human Pot1 (protection of telomeres) protein: cytolocalization, gene structure, and alternative splicing.
abstract: Fission yeast Pot1 (protection of telomeres) is a single-stranded telomeric DNA binding protein with a critical role in ensuring chromosome stability. A putative human homolog (hPot1) was previously identified, based on moderate sequence similarity with fission yeast Pot1 and telomere end-binding proteins from ciliated protozoa. Using indirect immunofluorescence, we show here that epitope-tagged hPot1 localizes to telomeres in interphase nuclei of human cells, consistent with a direct role in telomere end protection. The hPOT1 gene contains 22 exons, most of which are present in all cDNAs examined. However, four exons are subject to exon skipping in some transcripts, giving rise to five splice variants. Four of these are ubiquitously expressed, whereas the fifth appears to be specific to leukocytes. The resultant proteins vary significantly in their ability to form complexes with single-stranded telomeric DNA as judged by electrophoretic mobility shift assays. In addition to these splice variants, the Pot1 family is expanded by the identification of six more genes from diverse species. Pot1-like proteins have now been found in plants, animals, yeasts, and microsporidia.
authors.affiliation: Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Baumann
authors.forename: Elaine
authors.initials: E
authors.lastname: Podell
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Cech
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism*; D016415:Sequence Alignment; D000089804:Shelterin Complex; D034501:Telomere-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D035341:Telomeric Repeat Binding Protein 2 / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D009687:Nuclear Proteins; C440849:POT1 protein, human; D000089804:Shelterin Complex; D034501:Telomere-Binding Proteins; D035341:Telomeric Repeat Binding Protein 2; D004247:DNA