John Hopkins biophysicists have identified a “rocking” motion in a protein ensemble, a “back and forth” movement critical in the normal functioning of brain signaling molecules. The work could lead to advancements in neurological treatments.

The newly discovered “rocking receptor” is thought to be critical to the communication between nerve cells in the brain and spinal cord; the back-and-forth motion responsible for fully activating a protein.

The discovery may reveal multiple drug targets within the protein ensemble that could lead to treatments for neurological disorders such as epilepsy, schizophrenia, Parkinson’s and Alzheimer’s disease.

The researchers – led by Albert Lau, PhD, assistant professor of biophysics and biophysical chemistry at the Johns Hopkins University School of Medicine – believe the research may prove to be a critical.

Dr Lau says of the “rocking motion” discovery:

“We believe that our study is the first to show the molecular architecture and behaviour of a prominent neural receptor protein ensemble in a state of partial activation.”

Using a combination of methods, the team were able to tease apart the process of zero and full activation in cells to reveal the critical protein ensemble motion. Their methods included:

  • Computer modelling
  • Biophysical “imaging”
  • Biochemical analysis
  • Electrical monitoring.

The results of the study have been published in the journal Neuron.

The full activation of certain receptors required in synaptic transmission may be far more complex than previously understood, the researchers say.

Dr Lau explains that glutamate receptors reside within the outer envelope of every nerve cell in the brain and spinal cord. These receptors are responsible for changing chemical information into electrical information.

If these receptors are disabled, communication between nerve cells in the brain is sharply reduced, resulting in thought and normal brain function being severely compromised.

Malfunctioning receptors, Dr Lau says, have been linked with numerous neurological disorders and are therefore potential targets for drug therapies.

Lau continued to explain that each glutamate receptor is a united group of four protein segments that has a pocket for clamping down on glutamate like a Venus fly trap snaring a bug. Below the glutamate-binding segments are four other segments embedded in the cell’s outer envelope to form a channel for charged particles to flow through. When no glutamates are bound to the receptor, the channel is closed; full activation of the receptor and full opening of the channel occur when four glutamates are bound, each to a difference pocket.

It was previously thought that the level of receptor activation simply corresponded to the degree to which each glutamate-binding segment changed shape during the glutamate-binding process. However, the John Hopkins team were able to show that the four glutamate-binding segments, in addition to clamping down on glutamate, also rock back and forth in pairs when fewer than four glutamates are bound.

“It isn’t clear yet how this rocking motion affects receptor function, but we now know that activation depends on more than how much each glutamate-binding segment clamps down,” Albert Lau, Ph.D., assistant professor of biophysics and biophysical chemistry and research lead.

Development of drugs for neurological disorders have previously targeted the receptor focused on the four glutamate-binding pockets, rather than the motion involved within the successful execution of the process.

He adds:

“Our discovery of this molecular motion could aid the development of drugs by revealing additional drug-binding sites on the receptor.”

Written by Sally Burr