The voltage sensor of voltage-gated ion channels is a conserved protein domain that senses millivolt changes in transmembrane potential, to regulate ion permeation through the channel. A recently discovered protein, Ci-VSP, has a voltage sensor that is coupled not to an ion channel but to a phosphatidylinositide phosphosphatase, the activity of which depends on membrane potential.
In a new paper published in The Journal of Physiology, Murata and Okamura, from the Okazaki Institute for Integrative Bioscience, examine a voltage-sensitive phosphatase that converts an electrical to a chemical signal; they directly demonstrate that the enzyme activity of Ci-VSP changes in a voltage-dependent manner through the operation of the voltage sensor.
Prior to this work, it was unclear which phosphoinositides were the major substrates of the phosphatase activity, and whether depolarisation or hyperpolarisation induced the phosphatase activity. By expressing phosphoinositide-specific sensors in Xenopus oocytes and applying both electrophysiology and imaging of phosphoinositides, it was shown that enzyme activity is activated upon depolarisation (not upon hyperpolarisation), and that levels of both PtdIns(4,5)P2 and PtsIns(3,4,5)P3 are regulated by the operation of voltage sensor.
“Our findings identify common principles of the voltage sensor shared between voltage-gated ion channels and the voltage-sensing phosphatase," comment the authors.
"There is no question that the VSP is a much simpler model than ion channels for understanding the mechanisms of voltage sensing, and understanding the VSP will provide insights into the function of ion channels as well. Such knowledge is critical for understanding general mechanisms of voltage sensing and many disorders coupled with altered membrane excitabilities. The VSP’s ability to tune phosphoinositide phosphatase activity by voltage will also serve as an important molecular tool to understand mechanisms of tumor suppressor phosphatase, PTEN, and other phosphatases that underlie carcinogenesis and metabolic disorders."
Article: “Depolarization activates the phosphoinositide phosphatase Ci-VSP, as detected in Xenopus oocytes coexpressing sensors of PIP2”, by Yoshimichi Murata and Yasushi Okamura. 15 September 2007, The Journal of Physiology, 583.3, pp. 875–889.
- PHYSICAL SCIENCES
- EARTH SCIENCES
- LIFE SCIENCES
- SOCIAL SCIENCES
Subscribe to the newsletter
Stay in touch with the scientific world!
Know Science And Want To Write?
- Schrodinger's equation in 1834 - a wild ass guess (WAG) like atoms being knots or particles being strings?
- From The Great Wall To The Great Collider
- Would New Planet X Clear Its Orbit? - And Any Better Name Than "Planet Nine"?
- Double Dose Of Bad Earthquake News
- Skyscraper Tall Telescope For Hawaii Mountain - Should Astronomers Build It?
- Why Your Muscles Get Less Sore As You Stick With Your Gym Routine
- Why This New "Planet X" Is No Threat To Earth :).
- "Person killed by meteorite: http://indianexpress.com/article/india/india-news-india/vellore-explosion..."
- " Not to put words in the authors mouth I believe what he is referring to is the attribution of..."
- "This is all just fear-mongering, clap-trap! If things go according to these prediction, but no..."
- "like the sages of israel say g-d created the rules and he dont owe anyone anything weather this..."
- "This is not surprising. In fact in a cohort with autism in general who did not have this specific..."
- Here’s Why Surge in Hepatitis B Cases is No Surprise
- Whooping Cough Booster Declines Rapidly Over 4 Years
- Unapproved Stem Cell Therapies, a Public Health Menace
- Enjoying the Sun’s Vitamin D, While Blocking Skin Cancer
- Norovirus: From Satan’s Biohazard Lab To Your Duodenum
- Health Briefs: What You Missed Over the Weekend
- Allergy shots effective for baby boomers suffering from seasonal allergies
- Body temperature triggers newly developed polymer to change shape
- Biologists find genetic mechanism for 'extremophile' fish survival
- Some heart drugs and antibiotics show effective in fighting cancer
- The herbivore dilemma: How corn plants fights off simultaneous attacks