Related Experiment Videos
Testis-specific expression of an intronless gene encoding a human poly(A) polymerase
1Department of Chemistry and Center for Molecular Design and Synthesis, Korea Advanced Institute of Science and Technology, Taejon. ylee@mail.kaist.ac.kr
Abstract:
A mouse intronless gene, encoding a testis-specific poly(A) polymerase (mPAPT), was previously identified. mPAPT may play a role as a putative enzyme that is responsible for polyadenylation regulation during mouse spermatogenesis. In order to understand how PAPT genes are conserved in mammals, we isolated a human cDNA homolog encoding a human PAPT (hPAPT), which was specifically expressed in the testis. The structure of hPAPT was very similar to that of mPAPT. The about 100 residues at the C-terminal region of a nuclear poly(A) polymerase, PAP II, were missing in both PAPT proteins. An analysis of the genomic DNA showed that the hPAPT gene is an intronless gene that is similar to the mPAPT gene. Interestingly, the sequence homology between hPAPT and mPAPT was much lower than the homology between hPAP II and mPAP II. The phylogenetic analysis suggests that PAPTs arose through retrotransposition after the amphibian-amniote split during evolution.
Insights
Researchers identified a human testis-specific poly(A) polymerase (hPAPT) gene, similar to its mouse counterpart (mPAPT). These intronless genes likely arose via retrotransposition, suggesting conserved roles in mammalian spermatogenesis.
Area of Science:
- Molecular Biology
- Evolutionary Biology
- Reproductive Biology
Background:
- A mouse testis-specific poly(A) polymerase (mPAPT) gene was identified, potentially regulating polyadenylation during spermatogenesis.
- Understanding the evolutionary conservation of PAPT genes across mammals is crucial for elucidating their function.
Purpose of the Study:
- To isolate and characterize the human homolog of mPAPT (hPAPT) to investigate its conservation in mammals.
- To analyze the structural and genomic similarities and differences between human and mouse PAPT proteins and genes.
Main Methods:
- Isolation of human cDNA encoding hPAPT.
- Structural comparison of hPAPT and mPAPT.
- Genomic DNA analysis of the hPAPT gene.
- Phylogenetic analysis of PAPT gene evolution.
Main Results:
- A human cDNA homolog, hPAPT, specifically expressed in the testis, was isolated.
- hPAPT shares structural similarities with mPAPT, notably lacking C-terminal residues found in PAP II.
- The hPAPT gene is intronless, mirroring the mPAPT gene structure.
- Sequence homology between hPAPT and mPAPT is lower than between their respective PAP II counterparts.
- Phylogenetic analysis indicates PAPT genes originated from retrotransposition events post-amphibian-amniote divergence.
Conclusions:
- hPAPT is a testis-specific poly(A) polymerase with structural and genomic similarities to mPAPT.
- The low sequence homology suggests divergent evolution despite conserved intronless structure.
- PAPT genes likely evolved through retrotransposition, playing a conserved role in mammalian spermatogenesis.