title: The F-type 5' motif of mouse L1 elements: a major class of L1 termini similar to the A-type in organization but unrelated in sequence.
abstract: It has previously been shown that the L1 family in the mouse (L1Md) contains two alternative 5' ends called the A- and F-type sequences (1,2). We show here that the F-type element is a major class of murine L1 elements and report on the details of organization of the 5' motif of these F-type elements. Although the A- and F-type 5' sequences share no detectable sequence homology the organization of an F-type 5' end is strikingly similar to that of an A-type. That is, the F-type 5' sequences consist of a tandem array of a small number of 206 bp monomers while the A-type 5' motif consists of a tandem array of 208 bp monomers. All of the A-type elements characterized to date have a truncated monomer at the 5' end of the array. Many of the F-type elements are also terminated at the 5' end by a truncated copy but unlike the A-type elements some F-type elements terminate with a monomer which is within a few nucleotides of being complete. In addition the F-type consensus sequence, in contrast to the A-type sequence, shows homology (70%) to the body of the L1Md starting at the position where the monomer joins the rest of the L1 element.
authors.affiliation: Department of Microbiology and Immunology, University of North Carolina, Chapel Hill 27514.
authors.forename: R W
authors.initials: RW
authors.lastname: Padgett
authors.forename: C A
authors.initials: CA
authors.lastname: Hutchison
authors.forename: M H
authors.initials: MH
authors.lastname: Edgell
mesh_terms: D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D051379:Mice / Q000235:genetics*; D008969:Molecular Sequence Data; D012091:Repetitive Sequences, Nucleic Acid; D014158:Transcription, Genetic