Alternative titles; symbols
HGNC Approved Gene Symbol: PAPOLB
Cytogenetic location: 7p22.1 Genomic coordinates (GRCh38) : 7:4,857,738-4,862,030 (from NCBI)
Lee et al. (2000) cloned mouse Papolb, which they called Papt, from a testis cDNA library. Northern blot and RT-PCR analyses revealed expression limited to testis. The transcription level of Papolb in a 2-week-old mouse was much lower than that of the general poly(A) polymerase gene, Pap (PAPOLA; 605553). The ratio of Papt to Pap was reversed in testis of a 4-week-old mouse. Transient expression in HeLa cells showed fluorescence-tagged Papolb protein in both the nucleus and the cytoplasm.
By screening a human testis cDNA library using mouse Papt as probe, Lee et al. (2001) cloned PAPOLB, which they designated PAPT. The deduced 636-amino acid protein contains a catalytic core, an RNA-binding region, and a putative nuclear localization signal. Compared with human PAPII (PAPOLA), PAPT lacks about 100 C-terminal amino acids, including a second putative nuclear localization signal and part of the serine/threonine-rich domain. The 5-prime UTR of the PAPT cDNA shows features of a CpG island. Northern blot analysis detected major transcripts of 2.8 and 4.5 kb and a minor transcript of 8.0 kb in human testis. The 4.5-kb transcript was expressed at much lower levels in other tissues examined.
Lee et al. (2001) determined that the PAPOLB gene contains no introns.
Hartz (2006) mapped the PAPOLB gene to chromosome 7p22.1 based on an alignment of the PAPOLB sequence (GenBank AF218840) with the genomic sequence (build 35).
By Southern blot analysis, Lee et al. (2001) determined that PAPOLB is a single-copy gene.
Kashiwabara et al. (2002) developed mice deficient in Papolb, which they called Tpap. Both male and female mice were normal in health, size, and behavior; the males, however, were infertile. The absence of Tpap resulted in the arrest of spermiogenesis. Papolb-deficient mice displayed impaired expression of haploid-specific genes required for the morphogenesis of germ cells. Papolb deficiency also caused incomplete elongation of poly(A) tails of specific transcription factor mRNAs. Kashiwabara et al. (2002) concluded that Tpap governs germ cell morphogenesis by modulating specific transcription factors at the posttranscriptional and posttranslational levels.
Hartz, P. A. Personal Communication. Baltimore, Md. 6/12/2006.
Kashiwabara, S., Noguchi, J., Zhuang, T., Ohmura, K., Honda, A., Sugiura, S., Miyamoto, K., Takahashi, S., Inoue, K., Ogura, A., Baba, T. Regulation of spermatogenesis by testis-specific, cytoplasmic poly(A) polymerase TPAP. Science 298: 1999-2002, 2002. [PubMed: 12471261] [Full Text: https://doi.org/10.1126/science.1074632]
Lee, Y. J., Kim, H., Chung, J. H., Lee, Y. Testis-specific expression of an intronless gene encoding a human poly(A) polymerase. Molec. Cells 11: 379-385, 2001. [PubMed: 11459229]
Lee, Y. J., Lee, Y., Chung, J. H. An intronless gene encoding a poly(A) polymerase is specifically expressed in testis. FEBS Lett. 487: 287-292, 2000. [PubMed: 11150526] [Full Text: https://doi.org/10.1016/s0014-5793(00)02367-x]