Geometry plays a role in GPCR transmembrane signaling

September 26, 2012
In a recent JGP article, researchers developed a novel approach to study GPCR movement within a living cell. This image shows the grid used for modeling diffusion, with tracings from the image of a rod outer segment indicating disc perimeter (white) and incisures (orange). Credit: Najafi, M., et al. 2012. J. Gen. Physiol. 140:249-266.

A recent study in The Journal of General Physiology characterizes the movement of rhodopsin, a GPCR and member of a large family of transmembrane receptors responsible for many cellular responses and involved in many human diseases.

In living Xenopus rod photoreceptor cells, rhodopsin is found in stacks of disc membranes that are difficult to study due to their small size. Now, Peter Calvert (SUNY Upstate Medical University) and colleagues have developed an approach with two- that, for the first time, allows direct examination within the living cell of how the geometry of the micro-compartment will affect its signaling.

The team focused on the effect of micro-compartments formed by "incisures", radial membrane boundaries that segment the discs into smaller regions. These micro-compartments, defined by the rim and incisures, have a similar to that of a human or mouse rod photoreceptor disc, so that the total number of components in the GPCR signaling cascade are conserved, and the downstream effects of a captured photon of light are similar. Calvert and colleagues used a novel high-resolution approach to monitor fluorescently labeled rhodopsin as it diffused in the disc membrane.

The team developed a model of to interpret the results that explicitly took the measured micro-compartments into account, and found that the boundary geometry, not heterogeneity in diffusion or a "bound fraction," was sufficient to explain differences in the extent of diffusion or rhodopsin in different regions of the disc.

More information: Najafi, M., et al. 2012. J. Gen. Physiol. 140:249. Adler, E.M. 2012. J. Gen. Physio. 140:341.

Related Stories

Recommended for you

A cheaper, high-performance prosthetic knee

July 30, 2015

In the last two decades, prosthetic limb technology has grown by leaps and bounds. Today, the most advanced prostheses incorporate microprocessors that work with onboard gyroscopes, accelerometers, and hydraulics to enable ...

Crystal clear images uncover secrets of hormone receptors

July 31, 2015

Many hormones and neurotransmitters work by binding to receptors on a cell's exterior surface. This activates receptors causing them to twist, turn and spark chemical reactions inside cells. NIH scientists used atomic level ...

Flow means 'go' for proper lymph system development

July 27, 2015

The lymphatic system provides a slow flow of fluid from our organs and tissues into the bloodstream. It returns fluid and proteins that leak from blood vessels, provides passage for immune and inflammatory cells from the ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.