PSI Structural Biology Knowledgebase

PSI | Structural Biology Knowledgebase
Header Icons

Research Themes
Cell biology
Drug discovery
Infectious diseases
Membrane proteins
Novel Proteins
Protein design
Protein-protein interactions

Technology Topics
Target Selection
Protein Expression
Electron Microscopy
Mass Spectrometry
Hybrid/Integrative Methods
Dissemination Tools

E-Collection Research Themes: Cell biology

Related Articles

Community-Nominated Targets

Featured System - July 2015
The Community-Nominated Targets program has allowed PSI to collaborate with researchers on hundreds of systems of high biological significance.

Drug Discovery: Solving the Structure of an Anti-hypertension Drug Target

Featured Article - July 2015
Serial femtosecond crystallography is used to solve the structure of angiotensin II type 1 receptor.

Retrospective: 7,000 Structures Closer to Understanding Biology

Featured Article - July 2015
As PSI:Biology comes to a close this month, we take a look back at all the biological advances made by the PSI Network.

Design and Evolution: Unveiling Translocator Proteins

Featured Article - June 2015
Structural and functional analyses provide new insights on the physiological roles of TSPOs.

Signaling with DivL

Featured System - May 2015
DivL shares many structural features with other bacterial signaling proteins, but has been modified by evolution to reverse the typical directionality of signaling.

Signaling: A Platform for Opposing Functions

Featured Article - May 2015
A modeled structure reveals the regulatory complexities of a TORC1-interacting complex.

Signaling: Securing Lipid-Protein Partnership

Featured Article - May 2015
Crystal structures provide a glimpse into how phosphoinositides stabilize nuclear hormones.

Dynamic DnaK

Featured System - March 2015
PSI researchers have used an engineered version of DnaK to reveal the open state of an Hsp70 protein chaperone.

Iron-Sulfur Cluster Biosynthesis

Featured System - December 2014
PSI researchers are exploring the complex biological machinery that builds iron-sulfur clusters.

Mitochondrion: Flipping for UCP2

Featured Article - December 2014
NMR studies reveal how UCP2 facilitates translocation of protons across the mitochondrial membrane via fatty acids.

Mitochondrion: Setting a New TRAP1

Featured Article - December 2014
An asymmetric Hsp90 structure supports a new mechanism for coupling ATP hydrolysis with substrate turnover.

Power in Numbers

Featured System - August 2014
PSI researchers have determined the structure of a transcriptional regulator involved in quorum sensing in an important pathogenic bacterium.

Quorum Sensing: A Groovy New Component

Featured Article - August 2014
A first-in-family structure of a Pseudomonas-specific protein provides clues to its role in quorum sensing.

Quorum Sensing: E. coli Gets Involved

Featured Article - August 2014
The crystal structure of E. coli SdiA provides insights into substrate selectivity and oxidation-dependent regulation.

iTRAQing the Ubiquitinome

Technical Highlight - July 2014
An inflammatory signal triggers broad changes to protein ubiquitination and chromatin regulation in immune cells.

Microbiome: The Dynamics of Infection

Technical Highlight - September 2013
A combination of systems approaches reveals how Salmonella displaces commensal gut bacteria to establish infections.

Protein-Nucleic Acid Interaction: A Modified SAM to Modify tRNA

Featured Article - July 2013
Basic metabolism may seem quite old-school, but the structure of a biosynthetic enzyme offers several surprises.

Protein-Nucleic Acid Interaction: Versatile Glutamate

Featured Article - July 2013
A cyanobacterial transcription factor recognizes three consecutive cytosines in promoter DNA using a single glutamate residue.

PDZ Domains

Featured System - April 2013
PDZ domains are specialists in protein recognition, but PSI Biology researchers are revealing their abilities to bind to membranes as well.

Alpha-Catenin Connections

Featured System - March 2013
Structures of alpha-catenin and vinculin are revealing a highly dynamic interaction in adherens junctions.

Cell-Cell Interaction: A FERM Connection

Featured Article - March 2013
The structure of a KRIT1–HEG1 complex reveals a new binding mechanism for FERM domains.

Cell-Cell Interaction: Magic Structure from Microcrystals

Technical Highlight - March 2013
Structure determination of a membrane protein using poorly diffracting microcrystals illustrates a powerful new application of solid-state NMR spectroscopy.

Cell-Cell Interaction: Modulating Self Recognition Affinity

Featured Article - March 2013
Subtle changes that distinguish homophilic and heterophilic interactions in a cell surface molecule are revealed.

Bacterial Hemophores

Featured System - January 2013
PSI biology researchers are exploring the proteins that pathogenic bacteria use to gather scarce heme groups, and the iron ions they carry.

Archaeal Lipids

Featured System - December 2012
PSI:Biology Researchers have revealed how archaea build their unusually temperature-tolerant lipids.

Membrane Proteome: Capturing Multiple Conformations

Featured Article - December 2012
Four novel crystallized conformers of the betaine/Na+ symporter BetP suggest a structural mechanism for molecular transport.

Lethal Tendencies

Featured Article - October 2012
The crystal structure of MtfA reveals a self-inhibited member of the lethal factor family of endopeptidases.

Symmetry from Asymmetry

Featured Article - October 2012
Structural analysis of an intermediate filament protein reveals how an asymmetric dimeric coiled-coil assembles into a symmetric tetrameric structure.

A signal sensing switch

Featured Article - September 2012
The structure of the sensor complex for the TMAO receptor sheds light on bacterial two-component signaling.

Regulatory insights

Featured Article - September 2012
Structures of the JH2 pseudokinase domain provide clues to its role in normal and disease-associated JAK signaling.

AlkB Homologs

Featured System - August 2012
Evolution is a great tinkerer, and when cells discover a useful plan for a protein, it is often pressed to service in other capacities.

Budding ensemble

Featured Article - August 2012
An integration of several structural approaches has generated a model for how vesicle budding may be coordinated by ESCRT complexes.

Targeting Enzyme Function with Structural Genomics

Featured System - July 2012
Prediction of the function of a new enzyme based only on its sequence, or even on its structure, is still a major challenge, and will be a major prize for biomedical research when effective methods are developed.

The machines behind the spindle assembly checkpoint

Featured Article - June 2012
The crystal structure of the mitotic checkpoint complex is reported.

Chaperone interactions

Featured Article - April 2012
The structure of a yeast co-chaperone reveals interactions essential for Fe-S cluster biogenesis.

Pilus Assembly Protein TadZ

Featured System - April 2012
Many bacteria are covered with long filaments, called pili or fimbriae, that help them interact and attach to their environment.

Revealing the Nuclear Pore Complex

Featured System - March 2012
This is an exciting time for the study of the nuclear pore complex, the highway of transport between the cytoplasm and nucleus, and also a central player in nuclear organization and gene regulation.

Topping off the proteasome

Featured Article - March 2012
The structure of the entire proteasome complex provides insight into key functions while raising questions for future studies.

Twist to open

Featured Article - March 2012
A structure of an engineered potassium channel suggests a novel model for the gating mechanism.

Disordered Proteins

Featured System - February 2012
Looking through the thousands of structures in the PDB, we get the impression that proteins must have a stable, folded structure to be functional.

Analyzing an allergen

Featured Article - January 2012
Computational, structural, and biochemical analysis of peanut Ara h 1 gives insights into understanding and diagnosing nut allergies.

Making Lipopolysaccharide

Featured System - January 2012
Many bacteria surround themselves with a protective coat, to resist attack from antibiotics, predators, and the immune system.

Pulling on loose ends

Featured Article - January 2012
Structural analyses of the first identified activase for red-type Rubiscos reveal key insights into Rubisco activation.

Terminal activation

Featured Article - December 2011
The recent crystal structure of the human BIG2 Sec7 domain reveals a novel ARF-interacting motif that regulates ARF activation.

The Perils of Protein Secretion

Featured System - November 2011
Salmonella bacteria are tiny terrorists that infect cells and ultimately destroy them.

Bacterial Armor

Featured System - October 2011
Bacteria are found in nearly every corner of the world, evolving unique mechanisms to survive in their different environments.

TLR4 regulation: heads or tails?

Featured Article - October 2011
The crystal structure of the TLR4 regulator RP105–MD-1 reveals a unique head-to-head conformation and provides a glimpse into the mechanism of TLR4 regulation.

Ribose production on demand

Featured Article - September 2011
A previously unidentified enzymatic activity provides the driving force that leads to NADPH-independent ribose production.

Moving some metal

Featured Article - August 2011
The crystal structure of a copper-transporting P1B-type ATPase provides valuable insight into how mutations contribute to Menkes' and Wilson's diseases.

Looking for lipids

Featured Article - July 2011
The structure of UNC119 by itself and with a substrate shows how it binds lipids to regulate G protein trafficking.

Ribofuranosyl Binding Protein

Featured System - June 2011
Molecular recognition is at the very heart of life.

A molecular switch for neuronal growth

Featured Article - May 2011
Proteoglycans can exert opposing effects on neuronal growth by competing to control the oligomerization of a common cell surface receptor.

Cell wall recycler

Featured Article - May 2011
The crystal structure of the bacterial cell wall recycling protein Mpl reveals similarities as well as differences compared with functionally related Mur ligases.

Added benefits

Featured Article - April 2011
Biochemical, structural and genetic analyses reveal that the E. coli Cas1 protein YgbT belongs to a novel family of nucleases and that, in addition to antiviral immunity, the CRISPR–Cas system functions in DNA repair.

NMR challenges current protein hydration dogma

Technical Highlight - March 2011
For decades, scientists have struggled to understand protein interactions with water. NMR spectroscopy using reverse micelles suggests that the dynamics of water on the surface of proteins are quite variable and tend to cluster, overturning the current orthodoxy.

Nitrile Reductase QueF

Featured System - March 2011
Nature uses exotic chemistry to build its diverse collection of molecules.

Tip formin

Featured Article - March 2011
Single-molecule fluorescence polarization shows how mDia1 rotates along actin filaments.

Inhibiting factor

Featured Article - February 2011
Transcription initiation and elongation by RNA polymerase is inhibited by GreA. A recent crystal structure reveals the mechanism.

PASK staying active

Featured Article - February 2011
The PAS-domain regulated kinase (PASK) has been implicated in nutrition sensing and signaling to facilitate a metabolic response to changing nutritional status. The crystal structure of PASK now indicates a basis for the unusual activation properties and substrate selectivity of this kinase.

Tryptophanyl-tRNA Synthetase

Featured System - February 2011
Biology is full of surprises, and they often tell us important things about ourselves.

Regulating nitrogen assimilation

Featured Article - January 2011
By combining their efforts, researchers at two PSI centers provide new insights into a switch that controls nitrogen metabolism in microorganisms.

Subtle shifts

Featured Article - January 2011
The crystal structure of EF-Tu bound to the 70S ribosome solves a 40-year-old puzzle.


Featured System - December 2010
Proteins perform most of the nanoscale tasks inside of cells, but occasionally, they need help from more exotic molecules.

Function following form

Special - October 2010
The genome projects have yielded the sequences of many genes of unknown function. Insight into the mechanisms of action of the products of these genes can come from collaboration between structural biology and follow-up functional analyses..

tRNA Isopentenyltransferase MiaA

Featured System - August 2010
Cells always seem to find the best way of doing things.

Importance of extension for integrin

Featured Article - June 2010
An extended conformation of α5ß1 integrin is important for cell spreading and adhesion complex formation.


Featured System - April 2010
Most animals, including ourselves, use sophisticated eyes to see light.

Alg13 Subunit of N-Acetylglucosamine Transferase

Featured System - February 2010
Eukaryotic cells have an elaborate mechanism for adding sugar chains to their proteins.

Hemolysin BL

Featured System - January 2010
Bacteria are master weapon makers.


Featured System - December 2009
Cells typically deplete themselves of calcium, expending considerable energy to pump calcium ions out of the cell or into special compartments inside the cell.

Two-component signaling

Featured Article - December 2009
The structure of a sensor histidine kinase in complex with its effector response regulator reveals the details of the phosphoryl transfer reaction.

Network coverage

Featured Article - November 2009
A comprehensive atomic-resolution analysis of the centralmetabolic system of Thermotoga maritima sheds light on protein evolution.

Pseudouridine Synthase TruA

Featured System - November 2009
Evolution is a great tinkerer.

Unusual cell division

Featured Article - October 2009
Streptomyces' unique mechanism for cell division comes under the spotlight and reveals the importance of the protein SsgB.

Toxin-antitoxin VapBC-5

Featured System - September 2009
Living cells are full of surprises and mysteries.

Salicylic Acid Binding Protein 2

Featured System - August 2009
Centuries ago, both the ancient Greeks and native Americans discovered that willow bark and other plants can dull pain.

Proofreading RNA

Featured Article - July 2009
The structure of RNA polymerase II caught in the 'backtracked' state reveals how it ensures faithful transcription.Science 324, 1203-1206 (2009)

Ykul structure solves bacterial signaling puzzle

Featured Article - July 2009
The crystal structure of the phosphodiesterase YkuI reveals how it binds cyclic di-GMP and might explain its activation.J. Biol. Chem. 284, 13174-13184 (2009)

Hda and DNA Replication

Featured System - June 2009
Cell division requires careful bookkeeping.

Controlling p53

Featured Article - May 2009
Pirh2 promotes the ubiquitylation of the transcriptionally active form of p53 using an unusual two-site interaction strategy.Nat. Struc. Mol. Biol. 15, 1334-1342 (2008)

Mitotic checkpoint control

Featured Article - May 2009
The molecular basis of inhibition of the anaphase-promoting complex/cyclosome revealed.Science 323, 1477-1481 (2009)

Ribonuclease and Ribonuclease Inhibitor

Featured System - April 2009
The complex between ribonuclease and ribonuclease inhibitor is one of the tightest known intermolecular interactions, but researchers at the CESG are trying to change that.

The elusive helicase

Featured Article - April 2009
A combination of NMR, mutagenesis and biochemistry reveals the dynamic nature of the eIF4A/4G/4H helicase complex.Cell 136, 447-470 (2009)


Featured System - March 2009
The protozoan parasites that cause malaria multiply rapidly in the blood of infected individuals.

High-energy storage system

Featured Article - February 2009
Despite the cellular importance of inorganic polyphosphate, particularly in bacteria, exactly how it is processed is not known. Two new polyphosphate kinase structures should make things clearer.Proc Natl Acad Sci USA 105, 17730-17735 (2008)

A new class of bacterial E3 ubiquitination enzymes

Featured Article - January 2009
A structurally and mechanically distinct class of ubiquitin ligases has been discovered, and a single mutation changes this enzyme from a ligase to a potent thioesterase.Nature Struct. Mol. Biol. 15, 1293-1301 (2008)

Poly(A) RNA recognition

Featured Article - January 2009
Homodimerization of type II poly(A)-binding proteins prevents binding in the absence of RNA.Proc Natl Acad Sci. USA 105, 15317-15322 (2008)

Activating BAX

Featured Article - December 2008
The structure of the pro-apoptotic protein BAX with a bound BIM BH3 'death helix' reveals that a previously unsuspected binding site on BAX triggers activation of the BAX cell-death pathway.Nature 455, 1076-1081 (2008)

Scavenger Decapping Enzyme DcpS

Featured System - November 2008
Messenger RNA molecules are temporary molecules.

Bacteriophage Lambda cII Protein

Featured System - October 2008
Living cells are constantly making decisions: when to eat, when to move, even when to die.

New metal-binding domain

Featured Article - October 2008
J. Biol. Chem., doi:10.1074/jbc.M804746200 (2008)

Blocking AmtB

Featured Article - September 2008
Proc Natl Acad Sci USA 104, 42-47 (2007)


Featured System - September 2008
The repressor protein T-Rex has the difficult job of distinguishing the difference between NAD+ and NADH.

Aspartate Dehydrogenase

Featured System - August 2008
Aspartate dehydrogenase is a new enzyme discovered by Northeast Structural Genomics Consortium.

RNase T

Featured System - July 2008
Living cells are filled with RNases, but not highly destructive ones like our digestive RNase.


Featured System - May 2008
The cell is a busy place with thousands of things happening at once.
Structural Biology Knowledgebase ISSN: 1758-1338
Funded by a grant from the National Institute of General Medical Sciences of the National Institutes of Health