BioWiki

Protein spotlight

http://www.expasy.org/spotlight/

「Protein Spotlight」 (ISSN 1424-4721) は、スイスバイオインフォマティクス研究所Swiss-Protチームの月間レビューである。特定のタンパク質やタンパク質ファミリーについて、やさしく解説している。

最近の記事

http://au.expasy.org/spotlight/index.rdfから最新記事のフィードを取得できる。

  • life, a subtle balance by vgerrits (2018/07/26 10:56)
    Life is a continuous balance between what needs to remain, and what must disappear. We are not aware of it but our bodies unceasingly shed cells that have received orders to die, which is a necessary process if tissues are to be renewed or to stay healthy. It does seem an odd paradox, but this surprising phenomenon is an integral part of every living being and known as regulated cell death. There are different ways of dying, and cells are imaginative. One of the more select ways has been coined ferroptosis. Ferroptosis occurs when the level of iron-dependent lipid hydroperoxides has become toxic for a cell, which is then left to perish. But before this occurs, cells have to be equipped with the necessary means to prevent precocious poisoning, or they will never be able to get on with what they are expected to. This regulation of the level of toxins is ensured by a special version of an enzyme known as glutathione peroxidase 4, or GPX4, that carries a very rare amino acid in its active site: selenocysteine.
  • tainted by vgerrits (2018/06/21 18:16)
    It has happened to all of us. You are seated in a good restaurant and the waiter has just brought you the wine you ordered. He solemnly shows you the label. You nod, and he proceeds to slit open the lead seal with the tip of his corkscrew. Pealing the seal off the bottle neck, he then screws the screw into the cork which he extracts with a muffled pop. He may bring the cork to his nostrils and sniff it, then with one hand behind his back, he will carefully fill the glass of the person who is to inform him whether the wine tastes fine, or not. And on rare occasions, it does not. But you're never quite sure. So you ask the person sitting opposite whether they would care to try. And they're not sure either, so you both say to the waiter that the wine is lovely, thank you. Yet, over dinner, there's a slight musty taste each time you take a sip of wine. This characteristic faint off-taste - coined cork taint - is caused by the presence of chemical molecules known as chloroanisoles in the wine. Scientists recently characterized an enzyme, that they named chlorophenol O-methyltransferase, from the filamentous fungus Trichoderma longibrachiatum that is responsible for their production.
  • giving in to time by vgerrits (2018/05/19 11:19)
    Time runs its treacherous fingers along everything. The smoothed edges of a pebble. The polished wood of a staircase. The worn joints in our bones. Sometimes, even, the erosion of our memory. Every day, every hour, every minute, we get a little older. Until we reach that invisible threshold when we actually begin to feel the years, and what getting older means. Our pace becomes slower and our muscles, stiff. Our bodies gradually bend forward and parts cave in. One hand begins to shake. Our thoughts are not so nimble. And perhaps for the first time we overhear someone say that we are old. Yet it is less a question of us getting old, than our bodies giving in to time. Cells inside us are losing touch. Information is being lost. Metabolic pathways become hesitant. Cells become weary, stifle and die. Many factors are involved in the very complex process of ageing. One of them is Plasminogen activator inhibitor 1 - or PAI-1. Scientists, however, discovered that a particular mutation in PAI-1 may actually be partly responsible for lengthening a person's life as opposed to shortening it.
  • more to it by vgerrits (2018/04/19 11:01)
    Multitasking is not limited to computers. On a day-to-day basis, humans frequently deal with more than one thing at a time - for the sake of speed, convenience and no doubt productivity. We brush our teeth while taking a shower, eat a sandwich while answering mails, wash the dishes while calling a relative. Though we are pretty good at it, humans are far from the only multitaskers on this planet. We also harbour a few inside us. Just consider cells... One cell can synthesize proteins, while secreting others, repairing its cytoskeleton and maintaining its membrane. And we now know that the odd protein is also able to juggle with more than one task - thus applying yet another layer of obsolescence to the not-so-old "one gene, one protein, one function" hypothesis. Such is the case for a protein known as dual function macrocyclase-peptidase, or POPB. POPB is involved in making amatoxins, which are very small cyclic peptides found in some mushrooms and particularly poisonous when ingested.
  • it's a thin line by vgerrits (2018/03/23 07:20)
    One cell. One organism. One fate: male, or female. The way Nature designs things, you would expect traits as fundamental as those that make a boy a boy or a girl a girl, for instance, to be inscribed in their respective DNA from the very start. In a way they are, of course, but there is a subtlety: if what defines gender is for some reason missing, then the other sex may emerge almost by default. So the process is far more than a simple case of gender that is genetically predetermined. The same goes for Musca domestica, or the common housefly, as it does for many other animals. There seems to be a sort of switch which, when on or off, will produce one sex or the other. This particular part of the sex decision system is preserved in many organisms, and scientists are beginning to realise that the upstream mechanisms leading to the definitive sex switch are surprisingly diverse and, in the case of Musca domestica, can even change from fly to fly. But one thing is preserved: to become male or female, you need a factor that will ultimately push the on/off sex switch. In the housefly, that factor is Mdmd, or Musca domestica male determiner.
  • side effects by vgerrits (2018/02/23 08:25)
    Nature tiptoes along a sturdy yet fragile tightrope. DNA is its backbone and provides a basis from which every single living species on this planet emerges and prospers. Time, however, tampers with everything. Silver turns black. Fruit rots. And DNA undergoes mutations. But mutations have their good side too; without them, there would not be such a diversity of species that has ended up colonising most of the planet. We know that evolution relies on chemical changes that slip into DNA - and so into proteins - because they can help a species adapt better to its surroundings. Some mutations turn out to be less beneficial for some, however, and can give rise to havoc. This is perhaps what has happened between the Zika virus (ZIKV) and humans. Everyone has heard of the ZIKV outbreak in South America that began in 2015, during which many babies were born with undersized heads and brains, and diminished cognitive skills. Some scientists suggest that a mutation in a protein located on the virus's shell, and known as prM, is responsible for this form of microcephaly in human foetuses.
  • round in circles by vgerrits (2018/01/25 14:26)
    There will always be more to Nature than meets the eye. During the 1950s and the 1960s, the importance of RNA in protein synthesis gradually emerged. RNA has always been seen as a linear molecule, a bit like a sentence which has a beginning and an end, and is read from one end to the other, letter by letter, word by word. Yet in the 1970s, scientists discovered another kind of RNA molecule: one that was, to their surprise, circular. Circular RNAs were first thought to be biological oddities, something that had gone wrong in the process of transcribing a gene, and which drifted in a cell's cytoplasm the way flotsam would in the sea. But as the years went by and technology evolved, it became all too clear that there was far too much circular RNA swilling around cells for its presence to be purely accidental. Today, not only are researchers discovering that circular RNAs - or circRNAs - seem to be another way of regulating gene expression but some circRNAs can also give rise to proteins. One such circRNA is known as cir-ZNF609.
  • when the mind bends by vgerrits (2017/12/20 16:29)
    Science has its backlashes. Consider nuclear fission, or the drug thalidomide*. Psilocybin is also a discovery that brought trouble with it - though of a very different and milder kind. Psilocybin is none other than the magic referred to in "magic mushrooms". The compound was extracted from psilocybin mushrooms, and its chemical structure resolved in the late 1950s. The effects it had on the human mind were studied extensively by clinical psychiatrists in the 1960s; the intriguing results became known outside the laboratory, and readily adopted by the prevailing counterculture movements. It did take not long, however and understandably so, for magic mushrooms, like LSD, mescaline and other psychedelic drugs, to become illegal, making it very difficult for scientists to carry out research on them. Yet, they had been fast to recognise the beneficial effects psilocybin could have on patients suffering from psychiatric disorders, such as depression or schizophrenia for example. Since the turn of the millennium, and despite the administrative harassments, the interest in psilocybin has been rekindled. Recently, researchers discovered a set of four enzymes involved in the compound's synthesis: psiD, psiH, psiK and psiM.
  • whispers by vgerrits (2017/11/23 19:17)
    We all depend on cues. Without them, the notion of community would not exist. Cues are the cement of society, and their nature can be very diverse. Birds whistle. Hogs grunt. Plants give off scents. Fish use bioluminescence. Slugs release pheromones. Humans talk. Many species have more than one way of flinging cues to one another: while capable of emitting sounds, they can also discharge smells, touch each other and make gestures. Humans, for example, have brought signalling to a peak by adding clothes, tattoos, piercing, makeup, jewellery and all forms of bodily transformations to their repertoire to add refinement - and perhaps a touch of egocentricity - to their means of exchange. But though it may seem that individualism is, paradoxically, what drives communication these days, every signal is a manifestation of the belonging to a part - however small - of society. Many other animals have also evolved intricate means of communication. Ants, in particular. Over time, these insects have acquired an advanced form of social behaviour driven by these mysterious invisible cues called pheromones whose effects depend highly on a protein known as odorant receptor co-receptor, or Orco.
  • seeking past shelter by vgerrits (2017/10/26 10:29)
    Nothing can survive without the means to defend itself. If bacteria are unable to protect themselves from freezing temperatures, they perish. If we cannot fight off the flu virus, we pass away. If plants cannot ward off toxic fungi, they wilt and die. In fact, we all spend a lot of time shunning "stresses", of either biological (biotic) origin, or non-biological (abiotic) origin. The good part is that when an organism has managed to check an infection or deal with harsh conditions once, it does not forget and will react all the faster if the same thing occurs again. In other words, somehow and somewhere, memories are engraved in an organism. This is precisely how a vaccination works in humans. Needless to say, scientists have also found ways to prepare a plant's resistance mechanisms in advance by treating it with certain substances or presenting it with stressful environmental conditions. This is called plant defence priming. Researchers also observed that this acquired state of a plant can also be inherited, which is like passing down a form of instinct: that of knowing how to deal with the enemy. One protein is known to be involved in the priming process, and has no doubt a role in preserving this protective memory. It has been named protein Impaired in BABA-Induced Sterility 1, or IBS1.