Proteins in different cellular compartments and structures tagged with green fluorescent protein

All of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus.

- Cytoplasm

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Cell division

Process by which a parent cell divides, when a mother cell divides into two or more daughter cells.

Cell division in prokaryotes (binary fission) and eukaryotes (mitosis and meiosis)
Divisome and elongasome complexes responsible for peptidoglycan synthesis during lateral cell-wall growth and division.
Image of the mitotic spindle in a human cell showing microtubules in green, chromosomes (DNA) in blue, and kinetochores in red
Cell division over 42. The cells were directly imaged in the cell culture vessel, using non-invasive quantitative phase contrast time-lapse microscopy.
Kurt Michel with his phase-contrast microscope

In general, mitosis (division of the nucleus) is preceded by the S stage of interphase (during which the DNA replication occurs) and is often followed by telophase and cytokinesis; which divides the cytoplasm, organelles, and cell membrane of one cell into two new cells containing roughly equal shares of these cellular components.

Cell (biology)

Basic structural and functional unit of life forms.

Onion (Allium cepa) root cells in different phases of the cell cycle (drawn by E. B. Wilson, 1900)
Structure of a typical prokaryotic cell
Structure of a typical animal cell
Structure of a typical plant cell
Detailed diagram of lipid bilayer of cell membrane
A fluorescent image of an endothelial cell. Nuclei are stained blue, mitochondria are stained red, and microfilaments are stained green.
Deoxyribonucleic acid (DNA)
Human cancer cells, specifically HeLa cells, with DNA stained blue. The central and rightmost cell are in interphase, so their DNA is diffuse and the entire nuclei are labelled. The cell on the left is going through mitosis and its chromosomes have condensed.
Diagram of the endomembrane system
Prokaryotes divide by binary fission, while eukaryotes divide by mitosis or meiosis.
An outline of the catabolism of proteins, carbohydrates and fats
An overview of protein synthesis.
Within the nucleus of the cell (light blue), genes (DNA, dark blue) are transcribed into RNA. This RNA is then subject to post-transcriptional modification and control, resulting in a mature mRNA (red) that is then transported out of the nucleus and into the cytoplasm (peach), where it undergoes translation into a protein. mRNA is translated by ribosomes (purple) that match the three-base codons of the mRNA to the three-base anti-codons of the appropriate tRNA. Newly synthesized proteins (black) are often further modified, such as by binding to an effector molecule (orange), to become fully active.
Staining of a Caenorhabditis elegans highlights the nuclei of its cells.
Stromatolites are left behind by cyanobacteria, also called blue-green algae. They are the oldest known fossils of life on Earth. This one-billion-year-old fossil is from Glacier National Park in the United States.
Robert Hooke's drawing of cells in cork, 1665

Every cell consists of a cytoplasm enclosed within a membrane, which contains many biomolecules such as proteins and nucleic acids.


Type of protoplasm that makes up the cell nucleus, the most prominent organelle of the eukaryotic cell.

The protoplasmic material of the nucleus including the nucleolus labelled as nucleoplasm.

The nucleoplasm resembles the cytoplasm of a eukaryotic cell in that it is a gel-like substance found within a membrane, although the nucleoplasm only fills out the space in the nucleus and has its own unique functions.


The eukaryotic cytoskeleton. Actin filaments are shown in red, and microtubules composed of beta tubulin are in green.

The cytoskeleton is a complex, dynamic network of interlinking protein filaments present in the cytoplasm of all cells, excluding bacteria and archaea.

Cell signaling

Ability of a cell to receive, process, and transmit signals with its environment and with itself.

Different types of extracellular signaling
Differences between autocrine and paracrine signaling
Figure 2. Notch-mediated juxtacrine signal between adjacent cells.
Transmembrane receptor working principle
The AMPA receptor bound to a glutamate antagonist showing the amino terminal, ligand binding, and transmembrane domain, PDB 3KG2
A G Protein-coupled receptor within the plasma membrane.
VEGF receptors are a type of enzyme-coupled receptors, specifically tyrosine kinase receptors
Figure 3. Key components of a signal transduction pathway (MAPK/ERK pathway shown)
Signal transduction pathways that lead to a cellular response

Receptors are generally proteins located on the cell surface or within the interior of the cell such as the cytoplasm, organelles, and nucleus.


Membrane-bound organelle which is present in plant and fungal cells and some protist, animal, and bacterial cells.

Plant cell structure
Animal cell structure
The anthocyanin-storing vacuoles of Rhoeo spathacea, a spiderwort, in cells that have plasmolyzed

Strands of cytoplasm often run through the vacuole.


Living part of a cell that is surrounded by a plasma membrane.

Onion (Allium cepa) root cells in different phases of the cell cycle (drawn by E. B. Wilson, 1900)

In some definitions, it is a general term for the cytoplasm (e.g., Mohl, 1846), but for others, it also includes the nucleoplasm (e.g., Strasburger, 1882).

Golgi apparatus

Organelle found in most eukaryotic cells.

Micrograph of Golgi apparatus, visible as a stack of semicircular black rings near the bottom. Numerous circular vesicles can be seen in proximity to the organelle.
3D rendering of Golgi apparatus
Diagram of a single "stack" of Golgi
The Golgi apparatus (salmon pink) in context of the secretory pathway
Diagram of secretory process from endoplasmic reticulum (orange) to Golgi apparatus (magenta). 1. Nuclear membrane; 2. Nuclear pore; 3. Rough endoplasmic reticulum (RER); 4. Smooth endoplasmic reticulum (SER); 5. Ribosome attached to RER; 6. Macromolecules; 7. Transport vesicles; 8. Golgi apparatus; 9. Cis face of Golgi apparatus; 10. Trans face of Golgi apparatus; 11. Cisternae of the Golgi apparatus.
Two Golgi stacks connected as a ribbon in a mouse cell. Taken from the movie.
Three-dimensional projection of a mammalian Golgi stack imaged by confocal microscopy and volume surface rendered using Imaris software. Taken from the movie.

Part of the endomembrane system in the cytoplasm, it packages proteins into membrane-bound vesicles inside the cell before the vesicles are sent to their destination.



Microfilaments, also called actin filaments, are protein filaments in the cytoplasm of eukaryotic cells that form part of the cytoskeleton.


Proteasomes are protein complexes which degrade unneeded or damaged proteins by proteolysis, a chemical reaction that breaks peptide bonds.

Cartoon representation of a proteasome. Its active sites are sheltered inside the tube (blue). The caps (red; in this case, 11S regulatory particles) on the ends regulate entry into the destruction chamber, where the protein is degraded.
Top view of the proteasome above.
Schematic diagram of the proteasome 20S core particle viewed from one side. The α subunits that make up the outer two rings are shown in green, and the β subunits that make up the inner two rings are shown in blue.
Cartoon representation of the 26S proteasome.
Three distinct conformational states of the 26S proteasome. The conformations are hypothesized to be responsible for recruitment of the substrate, its irreversible commitment, and finally processing and translocation into the core particle, where degradation occurs.
Ribbon diagram of ubiquitin, the highly conserved protein that serves as a molecular tag targeting proteins for degradation by the proteasome
The ubiquitination pathway
A cutaway view of the proteasome 20S core particle illustrating the locations of the active sites. The α subunits are represented as green spheres and the β subunits as protein backbones colored by individual polypeptide chain. The small pink spheres represent the location of the active-site threonine residue in each subunit. Light blue chemical structures are the inhibitor bortezomib bound to the active sites.
The assembled complex of hslV (blue) and hslU (red) from E. coli. This complex of heat shock proteins is thought to resemble the ancestor of the modern proteasome.
Chemical structure of bortezomib (Boronated form of MG132), a proteasome inhibitor used in chemotherapy that is particularly effective against multiple myeloma
Bortezomib bound to the core particle in a yeast proteasome. The bortezomib molecule is in the center colored by atom type (carbon = pink, nitrogen = blue, oxygen = red, boron = yellow), surrounded by the local protein surface. The blue patch is the catalytic threonine residue whose activity is blocked by the presence of bortezomib.

In eukaryotes, proteasomes are located both in the nucleus and in the cytoplasm.