title: Loss of Octarepeats in two processed prion pseudogenes in the red squirrel, Sciurus vulgaris.
abstract: The N-terminal region of the mammalian prion protein (PrP) contains an 'octapeptide' repeat which is involved in copper binding. This eight- or nine-residue peptide is repeated four to seven times, depending on the species, and polymorphisms in repeat number do occur. Alleles with three repeats are very rare in humans and goats, and deduced PrP sequences with two repeats have only been reported in two lemur species and in the red squirrel, Sciurus vulgaris. We here describe that the red squirrel two-repeat PrP sequence actually represents a retroposed pseudogene, and that an additional and older processed pseudogene with three repeats also occurs in this species as well as in ground squirrels. We argue that repeat numbers may tend to contract rather than expand in prion retropseudogenes, and that functional prion genes with two repeats may not be viable.
authors.affiliation: Biomolecular Chemistry, 271 Nijmegen Center of Molecular Life Sciences, Radboud University, Nijmegen, The Netherlands. ole.madsen@wur.nl
authors.forename: Ole
authors.initials: O
authors.lastname: Madsen
authors.forename: Timothy T
authors.initials: TT
authors.lastname: Kortum
authors.forename: Marlinda
authors.initials: M
authors.lastname: Hupkes
authors.forename: Wouter
authors.initials: W
authors.lastname: Kohlen
authors.forename: Teun
authors.initials: T
authors.lastname: van Rheede
authors.forename: Wilfried W
authors.initials: WW
authors.lastname: de Jong
mesh_terms: D024506:5' Flanking Region / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D006579:Heterozygote; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000235:genetics; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011328:Prions / Q000737:chemistry* / Q000235:genetics*; D011544:Pseudogenes / Q000235:genetics*; D020449:Repetitive Sequences, Amino Acid / Q000235:genetics*; D012589:Sciuridae / Q000235:genetics*; D016415:Sequence Alignment
chemical_list: D010455:Peptides; D011328:Prions