Genetic individuality of intracisternal A-particles of Mus musculus

We have determined the nucleotide sequences of long terminal repeat (LTR) regions of Syrian hamster intracisternal A particle (IAP) genes. The size of the LTRs was 350 base-pairs (bp) and 376 bp in two clones, H10 and H18, respectively. Two LTRs at both ends of the IAP gene were linked to directly repeating 6 bp hamster sequences. Many structural features common to the integrated retroviral LTRs such as "CAT" box, "TATAA" box, polyadenylation signal, and terminal inverted repeat (3 bp), were present on each LTR. The estimated length of R region (about 60 bp) was similar to that of the murine leukemia-sarcoma virus. In contrast, the calculated U5 region of 54 bp was the shortest among those of the retroviruses so far studied. Furthermore, from the analysis of primer binding sites, phenylalanine tRNA was for the first time identified as a presumed primer tRNA for reverse transcription. These results clearly distinguish Syrian hamster IAP LTRs from other retroviral ones. Based on the comparison of the sequences between Syrian hamster and laboratory mouse LTRs, the structural features peculiar to the IAP LTRs and the origin of the IAP genes are discussed.

Section: Introductionmentioning

confidence: 97%

Long terminal repeat sequences of intracisternal A particle genes in the Syrian hamster genome: identification of tRNA^Pheas a putative primer tRNA

Ono

Ohishi

1983

“…As shown in other retrovirus particles, IAPs have particleassociated single-stranded poly(A)-containing RNAs (IAP RNAs) of 4 to 7 kb long (14)(15)(16). IAP RNA, however, has no apparent sequence homology with either type-B or type-C murine retroviral RNA (17) although a certain class of retroviruses endogenous to the Asian murine species, Mus caroli and Mus cervicolor, has been reported to share partial sequence homology with IAP RNA (18,19) DNA sequences complementary to mouse IAP RNA (IAP genes) are reiterated at about 1,000 copies per haploid genome of both normal and transformed cells in the inbred mouse (15,20,21) and localized dispersedly on many chromosomes (20). In contrast, the numbers of endogenous genes homologous to murine type-B and type-C retroviruses have been reported to be less than 1/20 of that of IAP genes present in inbred mouse genome.…”

Section: Introductionmentioning

confidence: 99%

Molecular cloning of retrovirus-like genes present in multiple copies in the Syrian hamster genome

Suzuki¹,

Kitasato

Kawakami³

et al. 1982

Endogenous retrovirus-like sequences homologous to intracisternal type-A particle (IAP) genes, which are present in the inbred mouse (Mus musculus) genome, were cloned from a Syrian hamster gene library. A typical hamster IAP gene was 7 kb long and segments homologous to long terminal repeat (IAP) sequences present in Mus musculus IAP genes were located at both ends of the gene. Contrary to the pattern found in the Mus musculus IAP genes, the organization of the cloned hamster IAP genes was not markedly polymorphic and deletion was not observed among these cloned genes. A sequence about 0.8 kb long and located close to the 3' end of the hamster IAP gene was well conserved in both IAP gene families, although they showed less overall homology with one another. The reiteration frequency of the hamster IAP genes was calculated to be 950 copies per haploid genome. Since such IAP genes with the above properties were not found in the genome of the Chinese hamster, whose progenitors diverged from those of the Syrian hamster about 7.5 Myr ago, the integration of a huge number of Syrian hamster IAP genes must have occurred subsequent to such divergence.

“…There are no close sequence homologies between the IAPs and representative type-B and type-C viruses of M. musculus (19), but IAPs do share partial sequence homology (2) with a distinctive class of retroviruses endogenous to the Asian murine species Mus cervicolor and Mus caroli (20).…”

Section: Introductionmentioning

confidence: 99%

Sequences homologous to retrovirus-like genes of the mouse are present in multiple copies in the Syrian hamster genome

Lueders

Kuff

1981

The genome of M. musculus contains many copies of DNA sequences homologous to the 35S RNA of intracisternal type-A particles (IAP) (1,2). A major class of IAP genes has been identified and isolated from a mouse library in Charon 4A (3). Cloned mouse IAP genes were used as probes to study homologous sequences in the DNA of other species. Sequences related to mouse IAP genes were detected in the DNAs from a variety of animal cells. DNAs from rat, gerbil, and hamster cells all gave strong reactions which could be localized to discrete restriction fragments on genomic blots. The reaction of Syrian hamster DNA was particularly strong. Fragments derived from different parts of the IAP gene all reacted with Syrian hamster DNA, and the reactive restriction fragments in the Syrian hamster DNA could be ordered with reference to the known restriction map of the IAP genes. The data suggest that sequences related to mouse IAP genes make up a 7 Kb unit in the Syrian hamster genome. Since the majority of the hamster sequences are quite divergent from those in the mouse, the ease with which they are detected suggests that they must be reiterated in the hamster genome.