Human Pot1 (protection of telomeres) protein: cytolocalization, gene structure, and alternative splicing

Mol Cell Biol. 2002 Nov;22(22):8079-87. doi: 10.1128/mcb.22.22.8079-8087.2002.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alternative Splicing
  • Amino Acid Sequence
  • Animals
  • Cell Line
  • DNA / metabolism
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism
  • Humans
  • Immunohistochemistry
  • Mice
  • Molecular Sequence Data
  • Nuclear Proteins / genetics*
  • Nuclear Proteins / metabolism*
  • Sequence Alignment
  • Telomere-Binding Proteins / chemistry
  • Telomere-Binding Proteins / genetics*
  • Telomere-Binding Proteins / metabolism*
  • Telomeric Repeat Binding Protein 2 / metabolism

Substances

  • DNA-Binding Proteins
  • Fungal Proteins
  • Nuclear Proteins
  • POT1 protein, human
  • Telomere-Binding Proteins
  • Telomeric Repeat Binding Protein 2
  • DNA