Selection Criteria: structures with acceptable covalent geometry, structures with favorable non-bond energy, structures with the least restraint violations 
Primary Citation of Related Structures:   2HX6
PubMed Abstract: 
The RegB endoribonuclease participates in the bacteriophage T4 life cycle by favoring early messenger RNA breakdown. RegB specifically cleaves GGAG sequences found in intergenic regions, mainly in translation initiation sites. Its activity is very low but can be enhanced up to 100-fold by the ribosomal 30 S subunit or by ribosomal protein S1 ...
The RegB endoribonuclease participates in the bacteriophage T4 life cycle by favoring early messenger RNA breakdown. RegB specifically cleaves GGAG sequences found in intergenic regions, mainly in translation initiation sites. Its activity is very low but can be enhanced up to 100-fold by the ribosomal 30 S subunit or by ribosomal protein S1. RegB has no significant sequence homology to any known protein. Here we used NMR to solve the structure of RegB and map its interactions with two RNA substrates. We also generated a collection of mutants affected in RegB function. Our results show that, despite the absence of any sequence homology, RegB has structural similarities with two Escherichia coli ribonucleases involved in mRNA inactivation on translating ribosomes: YoeB and RelE. Although these ribonucleases have different catalytic sites, we propose that RegB is a new member of the RelE/YoeB structural and functional family of ribonucleases specialized in mRNA inactivation within the ribosome.
Organizational Affiliation: 
ICSN-RMN, Institut de Chimie des Substances Naturelles, CNRS de Gif-sur-Yvette, 91190 Gif-sur-Yvette et Ecole Polytechnique, 91128 Palaiseau, France.
Selection Criteria: structures with acceptable covalent geometry, structures with favorable non-bond energy, structures with the least restraint violations