Serum albumin (SA) is the most abundant protein in the blood plasma of mammals. SA has a characteristic heart-shape structure and is a highly versatile protein. It helps maintain normal water levels in our tissues and carries almost half of all calcium ions in human blood. SA also transports some hormones, nutrients and metals throughout the bloodstream. Despite being very similar to our own SA, those from other animals can cause some mild allergies in people. Therefore, some scientists study SAs from humans and other mammals to learn more about what subtle structural or other differences cause immune responses in the body.

Related to entries 3744 and 3746

The TRPA1 protein is responsible for the burn you feel when you taste a bite of sushi topped with wasabi. Known therefore informally as the "wasabi receptor," this protein forms pores in the membranes of nerve cells that sense tastes or odors. Pungent chemicals like wasabi or mustard oil cause the pores to open, which then triggers a tingling or burn on our tongue. This receptor also produces feelings of pain in response to chemicals produced within our own bodies when our tissues are damaged or inflamed. Researchers used cryo-EM to reveal the structure of the wasabi receptor at a resolution of about 4 angstroms (a credit card is about 8 million angstroms thick). This detailed structure can help scientists understand both how we feel pain and how we can limit it by developing therapies to block the receptor. For more on cryo-EM see the blog post Cryo-Electron Microscopy Reveals Molecules in Ever Greater Detail.

These smooth muscle cells were derived from mouse neural crest stem cells. Red indicates smooth muscle proteins, blue indicates nuclei. Image and caption information courtesy of the California Institute for Regenerative Medicine.

In this video, Rice University scientists used molecular modeling with a mathematical algorithm called AWSEM (for associative memory, water-mediated, structure and energy model) and structural data to analyze how a transcription factor called nuclear factor kappa B (NFkB) is removed from DNA to stop gene activation. AWSEM uses the interacting energies of their components to predict how proteins fold. At the start, the NFkB dimer (green and yellow, in the center) grips DNA (red, to the left), which activates the transcription of genes. IkB (blue, to the right), an inhibitor protein, stops transcription when it binds to NFkB and forces the dimer to twist and release its hold on DNA. The yellow domain at the bottom of IkB is the PEST domain, which binds first to NFkB. For more details about this mechanism called molecular stripping, see here.

This illustration shows, in simplified terms, how the CRISPR-Cas9 system can be used as a gene-editing tool. The CRISPR system has two components joined together: a finely tuned targeting device (a small strand of RNA programmed to look for a specific DNA sequence) and a strong cutting device (an enzyme called Cas9 that can cut through a double strand of DNA). This frame (4 out of 4) shows a repaired DNA strand with new genetic material that researchers can introduce, which the cell automatically incorporates into the gap when it repairs the broken DNA.

For an explanation and overview of the CRISPR-Cas9 system, see the iBiology video, and find the full CRIPSR illustration here.

A crystal of bovine trypsin protein created for X-ray crystallography, which can reveal detailed, three-dimensional protein structures.

Histone proteins loop together with double-stranded DNA to form a structure that resembles beads on a string. See image 2561 for a labeled version of this illustration. Featured in The New Genetics.

A mouse's fat cells (red) are shown surrounded by a network of blood vessels (green). Fat cells store and release energy, protect organs and nerve tissues, insulate us from the cold, and help us absorb important vitamins.

This image was part of the Life: Magnified exhibit that ran from June 3, 2014, to January 21, 2015, at Dulles International Airport.

This image of human red blood cells was obtained with the help of a scanning electron microscope, an instrument that uses a finely focused electron beam to yield detailed images of the surface of a sample.

A crystal of bacterial alpha amylase protein created for X-ray crystallography, which can reveal detailed, three-dimensional protein structures.

C. elegans, a tiny roundworm, with a ribosomal protein glowing red and muscle fibers glowing green. Researchers used these worms to study a molecular pathway that affects aging. The ribosomal protein is involved in protein translation and may play a role in dietary restriction-induced longevity. Image created using confocal microscopy.
View group of roundworms here 6582.
View closeup of roundworms here 6583.

A peripheral nerve cell made from human embryonic stem cell-derived neural crest stem cells. The nucleus is shown in blue, and nerve cell proteins peripherin and beta-tubulin (Tuj1) are shown in green and red, respectively. Related to image 3263.

Active site of E. coli response regulator PhoB.

This image shows the structure of a synapse, or junction between two nerve cells in three dimensions. From the brain of a mouse.

Solution NMR structure of protein target WR41 (left) from C. elegans. Noting the unanticipated structural similarity to the ubiquitin protein (Ub) found in all eukaryotic cells, researchers discovered that WR41 is a Ub-like modifier, ubiquitin-fold modifier 1 (Ufm1), on a newly uncovered ubiquitin-like pathway. Subsequently, the PSI group also determined the three-dimensional structure of protein target HR41 (right) from humans, the E2 ligase for Ufm1, using both NMR and X-ray crystallography.

Image showing rhabdomeres (red), the light-sensitive structures in the fruit fly retina, and rhodopsin-4 (blue), a light-sensing molecule.

Student Christina Hueneke of the Midwest Center for Structural Genomics is overseeing a protein cloning robot. The robot was designed as part of an effort to exponentially increase the output of a traditional wet lab. Part of the center's goal is to cut the average cost of analyzing a protein from $200,000 to $20,000 and to slash the average time from months to days and hours.

A light microscope image of a cell from the endosperm of an African globe lily (Scadoxus katherinae). This is one frame of a time-lapse sequence that shows cell division in action. The lily is considered a good organism for studying cell division because its chromosomes are much thicker and easier to see than human ones. Staining shows microtubules in red and chromosomes in blue. Here, condensed chromosomes are clearly visible near the end of a round of mitosis.

Related to images 1010, 1011, 1012, 1013, 1014, 1015, 1016, 1017, 1019, and 1021.

Researchers used cryo-electron tomography (cryo-ET) to capture images of a rat pancreas cell that were then compiled and color-coded to produce a 3D reconstruction. Visible features include the folded sacs of the Golgi apparatus (copper), transport vesicles (medium-sized dark-blue circles), microtubules (neon-green rods), a mitochondria membrane (pink), ribosomes (small pale-yellow circles), endoplasmic reticulum (aqua), and lysosomes (large yellowish-green circles). See 6606 for a still image from the video.

A crystal of sheep hemoglobin protein created for X-ray crystallography, which can reveal detailed, three-dimensional protein structures.

To develop a system for studying cell motility in unnatrual conditions -- a microscope slide instead of the body -- Tom Roberts and Katsuya Shimabukuro at Florida State University disassembled and reconstituted the motility parts used by worm sperm cells.

In vivo vascular development in kdr:GFP frogs. Related to images 3403 and 3405.

X-ray co-crystal structure of Src kinase bound to a DNA-templated macrocycle inhibitor. Related to 3413, 3414, 3416, 3417, 3418, and 3419.

Hydra magnipapillata is an invertebrate animal used as a model organism to study developmental questions, for example the formation of the body axis.

On top, the brain of a sleep-deprived fly glows orange because of Bruchpilot, a communication protein between brain cells. These bright orange brain areas are associated with learning. On the bottom, a well-rested fly shows lower levels of Bruchpilot, which might make the fly ready to learn after a good night's rest.

Opioid receptors on the surfaces of brain cells are involved in pleasure, pain, addiction, depression, psychosis, and other conditions. The receptors bind to both innate opioids and drugs ranging from hospital anesthetics to opium. Researchers at The Scripps Research Institute, supported by the NIGMS Protein Structure Initiative, determined the first three-dimensional structure of a human opioid receptor, a kappa-opioid receptor. In this illustration, the submicroscopic receptor structure is shown while bound to an agonist (or activator). The structure is superimposed on a poppy flower, the source of opium.

On the left, a cross-section slice of a rat pancreas cell captured using cryo-electron tomography (cryo-ET). On the right, a 3D, color-coded version of the image highlighting cell structures. Visible features include the folded sacs of the Golgi apparatus (copper), transport vesicles (medium-sized dark-blue circles), microtubules (neon green), ribosomes (small pale-yellow circles), and lysosomes (large yellowish-green circles). Black line (bottom right of the left image) represents 200 nm. This image is a still from video 6609.

Insect brains, like the honeybee brain shown here, are very different in shape from human brains. Despite that, bee and human brains have a lot in common, including many of the genes and neurochemicals they rely on in order to function. The bright-green spots in this image indicate the presence of tyrosine hydroxylase, an enzyme that allows the brain to produce dopamine. Dopamine is involved in many important functions, such as the ability to experience pleasure. This image was captured using confocal microscopy.

Vibrio fischeri (2 mm in length) is the exclusive symbiotic partner of the Hawaiian bobtail squid, Euprymna scolopes. After this bacterium uses its flagella to swim from the seawater into the light organ of a newly hatched juvenile, it colonizes the host and loses the appendages. This image was taken using a scanning electron microscope.

DNA consists of two long, twisted chains made up of nucleotides. Each nucleotide contains one base, one phosphate molecule, and the sugar molecule deoxyribose. The bases in DNA nucleotides are adenine, thymine, cytosine, and guanine. See image 2541 for an unlabeled version of this illustration. Featured in The New Genetics.

This structure from an amyloid-forming prion protein shows one way beta sheets can stack. Image originally appeared in a December 2012 PLOS Biology paper.

This skyline of New York City was created by “printing” nanodroplets containing yeast (Saccharomyces cerevisiae) onto a large plate. Each dot is a separate yeast colony. As the colonies grew, a picture emerged, creating art. To make the different colors shown here, yeast strains were genetically engineered to produce pigments naturally made by bacteria, fungi, and sea creatures such as coral and sea anemones. Using genes from other organisms to make biological compounds paves the way toward harnessing yeast in the production of other useful molecules, from food to fuels and drugs.

Circadian rhythms are physical, mental, and behavioral changes that follow a 24-hour cycle. Typical circadian rhythms lead to high energy during the middle of the day (10 a.m. to 1 p.m.) and an afternoon slump. At night, circadian rhythms cause the hormone melatonin to rise, making a person sleepy.

Learn more in NIGMS’ circadian rhythms featured topics page.

See 6612 for the Spanish version of this infographic.

A rendering of an activity biosensor image overlaid with a cell-centered frame of reference used for image analysis of signal transduction. This is an example of NIH-supported research on single-cell analysis. Related to 2798 , 2799, 2800, 2801 and 2803.

Misfolded proteins (green) within mitochondria (red). Related to video 5877.

Cilia (cilium in singular) are complex molecular machines found on many of our cells. One component of cilia is the doublet microtubule, a major part of cilia’s skeletons that give them support and shape. This animated image is a partial model of a doublet microtubule’s structure based on cryo-electron microscopy images. Video can be found here 6549.

Human embryonic stem cells were differentiated into cells like those found in the pancreas (blue), which give rise to insulin-producing cells (red). When implanted in mice, the stem cell-derived pancreatic cells can replace the insulin that isn't produced in type 1 diabetes. Image and caption information courtesy of the California Institute for Regenerative Medicine.

This photo shows a Varian Unity Inova 900 MHz, 21.1 T standard bore magnet Nuclear Magnetic Resonnance (NMR) spectrometer. NMR spectroscopy provides data used to determine the structures of proteins in solution, rather than in crystal form, as in X-ray crystallography. The technique is limited to smaller proteins or protein fragments in a high throughput approach.

Structure of the bacterial antitoxin protein GhoS. GhoS inhibits the production of a bacterial toxin, GhoT, which can contribute to antibiotic resistance. GhoS is the first known bacterial antitoxin that works by cleaving the messenger RNA that carries the instructions for making the toxin. More information can be found in the paper: Wang X, Lord DM, Cheng HY, Osbourne DO, Hong SH, Sanchez-Torres V, Quiroga C, Zheng K, Herrmann T, Peti W, Benedik MJ, Page R, Wood TK. A new type V toxin-antitoxin system where mRNA for toxin GhoT is cleaved by antitoxin GhoS. Nat Chem Biol. 2012 Oct;8(10):855-61. Related to 3428.

The G switch allows our bodies to respond rapidly to hormones. G proteins act like relay batons to pass messages from circulating hormones into cells. A hormone (red) encounters a receptor (blue) in the membrane of a cell. Next, a G protein (green) becomes activated and makes contact with the receptor to which the hormone is attached. Finally, the G protein passes the hormone's message to the cell by switching on a cell enzyme (purple) that triggers a response. See image 2536 and 2537 for other versions of this image. Featured in Medicines By Design.

Atomic model of the membrane region of the mitochondrial ATP synthase built into a cryo-EM map at 3.6 Å resolution. ATP synthase is the primary producer of ATP in aerobic cells. Drugs that inhibit the bacterial ATP synthase, but not the human mitochondrial enzyme, can serve as antibiotics. This therapeutic approach was successfully demonstrated with the bedaquiline, an ATP synthase inhibitor now used in the treatment of extensively drug resistant tuberculosis.

More information about this structure can be found in the Science paper ”Atomic model for the dimeric F0 region of mitochondrial ATP synthase” by Guo et. al.

This 2-hour-old fly embryo already has a blueprint for its formation, and the process for following it is so precise that the difference of just a few key molecules can change the plans. Here, blue marks a high concentration of Bicoid, a key signaling protein that directs the formation of the fly's head. It also regulates another important protein, Hunchback (green), that further maps the head and thorax structures and partitions the embryo in half (red is DNA). The yellow dots overlaying the embryo plot the concentration of Bicoid versus Hunchback proteins within each nucleus. The image illustrates the precision with which an embryo interprets and locates its halfway boundary, approaching limits set by simple physical principles. This image was a finalist in the 2008 Drosophila Image Award.

This sculpture made of purple and clear glass beads depicts bacteriophage Phi174, a virus that infects bacteria. It rests on a surface that portrays an adaptive landscape, a conceptual visualization. The ridges represent the gene combinations associated with the greatest fitness levels of the virus, as measured by how quickly the virus can reproduce itself. Phi174 is an important model system for studies of viral evolution because its genome can readily be sequenced as it evolves under defined laboratory conditions.

Pigment cells are cells that give skin its color. In fishes and amphibians, like frogs and salamanders, pigment cells are responsible for the characteristic skin patterns that help these organisms to blend into their surroundings or attract mates. The pigment cells are derived from neural crest cells, which are cells originating from the neural tube in the early embryo. This image shows pigment cells from pearl danio, a relative of the popular laboratory animal zebrafish. Investigating pigment cell formation and migration in animals helps answer important fundamental questions about the factors that control pigmentation in the skin of animals, including humans. Related to images 5754, 5755, 5757 and 5758.

Mosquito larvae with genes edited by CRISPR swimming in water. This species of mosquito, Culex quinquefasciatus, can transmit West Nile virus, Japanese encephalitis virus, and avian malaria, among other diseases. The researchers who took this video optimized the gene-editing tool CRISPR for Culex quinquefasciatus that could ultimately help stop the mosquitoes from spreading pathogens. The work is described in the Nature Communications paper "Optimized CRISPR tools and site-directed transgenesis towards gene drive development in Culex quinquefasciatus mosquitoes" by Feng et al. Related to images 6769 and 6770.

The lubber grasshopper, found throughout the southern United States, is frequently used in biology classes to teach students about the respiratory system of insects. Unlike mammals, which have red blood cells that carry oxygen throughout the body, insects have breathing tubes that carry air through their exoskeleton directly to where it's needed. This image shows the breathing tubes embedded in the weblike sheath cells that cover developing egg chambers.

This image was part of the Life: Magnified exhibit that ran from June 3, 2014, to January 21, 2015, at Dulles International Airport.

Cell-like compartments that spontaneously emerged from scrambled frog eggs. Endoplasmic reticulum (red) and microtubules (green) are visible. Image created using epifluorescence microscopy.

For more photos of cell-like compartments from frog eggs view: 6584, 6585, 6591, 6592, and 6593.

For videos of cell-like compartments from frog eggs view: 6587, 6588, 6589, and 6590.

Sepsis is the body’s overactive and extreme response to an infection. More than 1.7 million people get sepsis each year in the United States. Without prompt treatment, sepsis can lead to tissue damage, organ failure, and death. Many NIGMS-supported researchers are working to improve sepsis diagnosis and treatment. Learn more with our sepsis featured topic page.

See 6551 for the Spanish version of this infographic.

The G switch allows our bodies to respond rapidly to hormones. G proteins act like relay batons to pass messages from circulating hormones into cells. A hormone (red) encounters a receptor (blue) in the membrane of a cell. Next, a G protein (green) becomes activated and makes contact with the receptor to which the hormone is attached. Finally, the G protein passes the hormone's message to the cell by switching on a cell enzyme (purple) that triggers a response. See image 2536 and 2538 for other versions of this image. Featured in Medicines By Design.

RNA incorporated into the CRISPR surveillance complex is positioned to scan across foreign DNA. Cryo-EM density from a 3Å reconstruction is shown as a yellow mesh.