Genetics & Molecular Biology

Ever wonder what the smallest protein is? Apparently it's TRP-Cage, a protein with only 20 amino acids derived from the saliva of Gila monsters.

Trp-cage - smallest protein

You can find the structure file and images in the PDB database ( with PDB ID = 1L2Y. This highly stable mini-protein is important for studies of protein stability, protein folding, and 3D structure.

Even with this small size, it displays secondary structural elements, such as an alpha helix, found in many proteins. So far there are no known proteins with less than 20 residues, but we'll see what happens in the future.

The longest human protein is Titin with 34,350 amino acids. The smallest human protein is 44 amino acids but it could be an abortive translation from the 5' UTR of another mRNA. The smallest functional polypeptide is glutathione with only three amino acids.

BTW, proline is technically not even an amino acid much less a polypeptide. Chignolin is a man-made decapeptide so if you synthesize a GG dipeptide, it would be the smallest possible amino acid polymer.

Scientists have altered cardiac muscle cells to make them controllable with light and showed an ability to cause conditions such as arrhythmia in genetically modified mice, which opens up new possibilities for researching the development and therefore treatment of arrhythmias. 

Tobias Brügmann and his colleagues from the University of Bonn’s Institute of Physiology I used a “channelrhodopsin” for their experiments - a type of light sensor. At the same time, it can act as an ion channel in the cell membrane because when stimulated with blue light, this channel opens, and positive ions flow into the cell. This causes a change in the cell membrane’s pressure, which stimulates cardiac muscle cells to contract.
Stem cells help regenerate or repair damaged tissues, primarily by releasing growth factors that encourage existing cells in the human body to function and grow.

There has been an ongoing ethical controversy about human embryonic stem cell research but progress has been made nicely using adult stem cells, such as from marrow donors.
Proteins are the heavy lifters of cells, doing numerous tasks, but how the shape of a protein determines function remains one of the most important questions in the physics of biology.

Proteins are not the static, Lego-like objects you might see in an x-ray photograph in a textbook, they are made from long chains of amino acids scrunched into various blobs and a protein is always changing to slightly different structural arrangements due to thermal motion of its atoms. Even a modest-sized protein like myoglobin has an unimaginable number of possible arrangements of its atoms and each of these arrangements slightly changes its function.

We accept that genetics make some people smarter though few consider instead that genes may be making us dumber, but deleting the RGS14 gene in mice did make them smarter - by unlocking a mysterious region of the brain considered to be relatively inflexible, scientists at Emory University School of Medicine have found.

Bring on the psychic fans!

Premature ovarian failure (POF) is when a woman's ovaries stop working before she is 40.  Missed periods are usually the first sign of POF. Later symptoms may be similar to those of natural menopause. 

Most women with POF cannot get pregnant naturally. Fertility treatments help a few women; others use donor eggs to have children. There is no treatment that will restore normal ovarian function, though many health care providers suggest taking hormones until age 50.   According to the International Premature Ovarian Failure Association, between 1 and 4% of women suffer from POF – equivalent to between 250,000 and 1 million women in the USA alone.
Researchers say they have found 13 genes linked to human body mass.

Starting with DNA samples extracted from Icelanders' white blood cells banked in 1991 and 2002 by scientists there as part of the AGES–Reykjavik study of individuals in the general population, scientists used a customized, genome-wide profiling method dubbed CHARM (comprehensive high-throughput arrays for relative methylation) to look for regions that were the most variable, all chemically marked by DNA methylation. 

The DNA methylation analyses revealed epigenetic fingerprints which are unique to each individual and remain stable over time and may also be associated with various common traits including risks for common, complex diseases such as cancer and other conditions. 
An important enzyme that acts in the nervous system may lead to new treatments for conditions such as Alzheimer's and Parkinson's disease.

Our cells contain a network of tubes known as microtubules that are made of protein and serve as tracks for the shuttling of materials from one part of the cell to another.   Microtubules in parts of neurons in the brain that send signals, for example, are loaded with chemical additions called acetylation marks. Microtubules in parts of neurons that receive signals, on the other hand, have few. 
A research team says they have discovered one of the key drivers of human evolution and diversity, accounting for changes that occur between different generations of people.

Professor Alec Jeffreys, who discovered DNA fingerprinting at the University of Leicester in 1984, and has spent the decades since investigating what he describes as "pretty bizarre bits of DNA" - highly variable repeated parts of DNA called 'minisatellites' - found in the human genome. Jeffreys observed that these seemed to be changing and "picking up mutations at an extraordinary rate" when compared to other DNA.