Polynucleotide phosphorylase
| Polynucleotide Phosphorylase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
ExPASy NiceZyme view | | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / QuickGO | ||||||||
| |||||||||
Polynucleotide Phosphorylase (PNPase) is a bifunctional enzyme with a phosphorolytic 3' to 5' exoribonuclease activity and a 3'-terminal oligonucleotide polymerase activity.[2] That is, it dismantles the RNA chain starting at the 3' end and working toward the 5' end.[1] It also synthesizes long, highly heteropolymeric tails in vivo. It accounts for all of the observed residual polyadenylation in strains of Escherichia coli missing the normal polyadenylation enzyme.[1] Discovered by Marianne Grunberg-Manago working in Severo Ochoa's lab in 1955, the RNA-polymerization activity of PNPase was initially believed to be responsible for DNA-dependent synthesis of messenger RNA, a notion that was disproven by the late 1950s.[3][4]
It is involved in
In humans, the enzyme is encoded by the PNPT1 gene. In its active form, the protein forms a ring structure consisting of three PNPase molecules. Each PNPase molecule consists of two
The same abbreviation (PNPase) is also used for another, otherwise unrelated enzyme, Purine nucleoside phosphorylase.
| Human PNPase I | |||||||
|---|---|---|---|---|---|---|---|
| Identifiers | |||||||
| Symbol | PNPASE | ||||||
| Alt. symbols | PNPase, OLD35, old-35 | ||||||
Chr. 2 p15 | |||||||
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References
External links
- Polynucleotide+Phosphorylase at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
