| Autor: |
Clyde K. Yamashita, Debora B. Farber, N. B. Akhmedov, Jennifer Shih, Natik Piri |
| Rok vydání: |
2003 |
| Předmět: |
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| Zdroj: |
Journal of Biological Chemistry. 278:36999-37005 |
| ISSN: |
0021-9258 |
| Popis: |
The catalytic core of photoreceptor-specific cGMP-phosphodiesterase (PDE) consists of two subunits, PDEα and PDEβ, that are homologous and have similar domain organization but are encoded by different genes. We have examined the PDEα and PDEβ mRNA steady-state and protein levels as well as the biosynthesis rate of these proteins in developing and fully differentiated retinas. We have also determined the translational efficiency of PDE subunits and the role of their mRNA structures in regulating protein synthesis. In mature retinas, PDEα and PDEβ are represented by ∼1.5 × 108 and 7.5 × 108 copies/μg retinal mRNA, respectively. The levels of these transcripts in developing photoreceptors (P10) are approximately 75% of those at P30. Quantification of protein concentration indicated that PDEα and PDEβ are equally expressed in developing and fully differentiated photoreceptors. Furthermore, the PDEα/PDEβ ratios obtained throughout a 2-h pulsechase period revealed a similar turnover rate for both subunits. The observed discordance between the mRNA and protein levels of PDEα and PDEβ suggested post-transcriptional regulation of their expression. We found that PDEα mRNA is translated more efficiently than either of the two PDEβ transcripts expressed in retina. Therefore, the lower level of PDEα mRNA is compensated by its more efficient translation to achieve equimolar expression with PDEβ. We also analyzed the effect of PDEα and PDEβ mRNA 5′- and 3′-untranslated regions as well as that of their coding regions on protein synthesis. We determined that the PDE-coding regions play a critical role in the differential translation of these subunits. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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