Structural highlights
Function
[ANGI_CHICK] Binds to actin on the surface of endothelial cells; once bound, angiogenin is endocytosed and translocated to the nucleus. Stimulates ribosomal RNA synthesis including that containing the initiation site sequences of 45S rRNA. Cleaves tRNA within anticodon loops to produce tRNA-derived stress-induced fragments (tiRNAs) which inhibit protein synthesis and triggers the assembly of stress granules (SGs). Angiogenin induces vascularization of normal and malignant tissues. Angiogenic activity is regulated by interaction with RNH1 in vivo (By similarity).
Publication Abstract from PubMed
Ribonuclease inhibitor (RI) is a conserved protein of the mammalian cytosol. RI binds with high affinity to diverse secretory ribonucleases (RNases) and inhibits their enzymatic activity. Although secretory RNases are found in all vertebrates, the existence of a non-mammalian RI has been uncertain. Here, we report on the identification and characterization of RI homologs from chicken and anole lizard. These proteins bind to RNases from multiple species, but exhibit much greater affinity for their cognate RNases than for mammalian RNases. To reveal the basis for this differential affinity, we determined the crystal structure of mouse, bovine, and chicken RI.RNase complexes to a resolution of 2.20, 2.21, and 1.92A, respectively. A combination of structural, computational, and bioinformatic analyses enabled the identification of two residues that appear to contribute to the differential affinity for RNases. We also found marked differences in oxidative instability between mammalian and non-mammalian RIs, indicating evolution toward greater oxygen-sensitivity in RIs from mammalian species. Taken together, our results illuminate the structural and functional evolution of RI, along with its dynamic role in vertebrate biology.
Functional Evolution of Ribonuclease Inhibitor: Insights from Birds and Reptiles.,Lomax JE, Bianchetti CM, Chang A, Phillips GN Jr, Fox BG, Raines RT J Mol Biol. 2014 Jun 15. pii: S0022-2836(14)00287-3. doi:, 10.1016/j.jmb.2014.06.007. PMID:24941155[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Lomax JE, Bianchetti CM, Chang A, Phillips GN Jr, Fox BG, Raines RT. Functional Evolution of Ribonuclease Inhibitor: Insights from Birds and Reptiles. J Mol Biol. 2014 Jun 15. pii: S0022-2836(14)00287-3. doi:, 10.1016/j.jmb.2014.06.007. PMID:24941155 doi:http://dx.doi.org/10.1016/j.jmb.2014.06.007
