title: The sequence of a large L1Md element reveals a tandemly repeated 5' end and several features found in retrotransposons.
abstract: The complete nucleotide sequence of a 6,851-base pair (bp) member of the L1Md repetitive family from a selected random isolate of the BALB/c mouse genome is reported here. Five kilobases of the element contains two overlapping reading frames of 1,137 and 3,900 bp. The entire 3,900-bp frame and the 3' 600 bp of the 1,137-bp frame, when compared with a composite consensus primate L1 sequence, show a ratio of replacement to silent site differences characteristic of protein coding sequences. This more closely defines the protein coding capacity of this repetitive family, which was previously shown to possess a large open reading frame of undetermined extent. The relative organization of the 1,137- and 3,900-bp reading frames, which overlap by 14 bp, bears resemblance to protein-coding, mobile genetic elements. Homology can be found between the amino acid sequence of the 3,900-bp frame and selected domains of several reverse transcriptases. The 5' ends of the two L1Md elements described in this report have multiple copies, 4 2/3 copies and 1 2/3 copy, of a 208-bp direct tandem repeat. The sequence of this 208-bp element differs from the sequence of a previously defined 5' end for an L1Md element, indicating that there are at least two different 5' end motifs for L1Md.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001482:Base Composition; D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes; D004251:DNA Transposable Elements; D005796:Genes; D005914:Globins / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D010802:Phylogeny; D012091:Repetitive Sequences, Nucleic Acid; D012190:Retroviridae / Q000235:genetics
chemical_list: D004251:DNA Transposable Elements; D005914:Globins; D004262:DNA Restriction Enzymes