Tidy motor protein folds away when the job is done

October 3, 2006

A discovery by University of Leeds researchers has revealed how a motor protein shuts itself down and becomes compact when it has no cargo to carry. It then goes in search of more cargo, perhaps carried by other passing proteins.

The discovery is significant, because the protein, called myosin 5, is part of a large family of motor proteins involved in a wide range of important bodily processes, including hearing, muscle contraction, digestion and neural transmission – the delivery of messages from the brain to different parts of the body.

“Some fatal seizures can be caused by a breakdown in myosin 5 activity,” says Dr Peter Knight of the Leeds research team. “By increasing our understanding of the process, we can start to address the problems caused when it doesn’t work. Of course there are still many questions that need answering, but we now have a model on which to base potential bio-nanotechnology molecular systems that could replicate the process to deliver molecules of our choosing – such as targeted drug therapies – to specific sites.”

The new discovery builds on the existing work of the Molecular Contractility Group of the University’s Astbury Centre for Structural Molecular Biology, who together with colleagues from the National Institutes of Health in the US, first showed how myosin 5 ‘walks’ to its destination.

Myosin 5 molecules have two elongated heads attached to one end of a tail. Each head comprises a motor domain and a lever. At the other end of the tail is a pair of cargo-binding domains. In cells, myosin 5 is able to transport cargo because the two motor domains bind alternately to a filament called F-actin and take rapid strides along it by tilting the levers, like a pair of legs walking.

However, the filament it travels on is a one-way track, so myosin can only travel in one direction on its own. But once the cargo has been delivered – whether it is neurotransmitter chemicals to make a muscle contract or a package of pigments for a strand of hair – until now no-one knew what happened next.

Dr Kavitha Thirumurugan of the Leeds team commented: “It now seems that once its job is completed, myosin 5 folds up and the cargo binding domain does double duty by shutting down the motor, preventing myosin 5 from aimlessly wandering around. How it finds its next cargo we don’t yet know, but maybe it is picked up and carried there by proteins travelling in the other direction to start the cycle again. It’s a bit like a clockwork train network.”

Source: University of Leeds

Explore further: Protein harnesses power of 'silly walks'

Related Stories

Unlocking long-hidden mechanisms of plant cell division

September 25, 2014

Along with copying and splitting DNA during division, cells must have a way to break safely into two viable daughter cells, a process called cytokinesis. But the molecular basis of how plant cells accomplish this without ...

Hitchhiking nanotubes show how cells stir themselves

May 30, 2014

(Phys.org) —Chemical engineers from Rice University and biophysicists from Georg-August Universität Göttingen in Germany and the VU University Amsterdam in the Netherlands have successfully tracked single molecules inside ...

Study visualizes mRNA transport in test tube

July 15, 2013

(Phys.org) —Much of biomedical science – both mystifying and awe-inspiring to the lay public – depends on an unwavering focus on things that can't be easily seen, like the inner-workings of cells, in order to determine ...

Recommended for you

Seeing quantum motion

August 28, 2015

Consider the pendulum of a grandfather clock. If you forget to wind it, you will eventually find the pendulum at rest, unmoving. However, this simple observation is only valid at the level of classical physics—the laws ...

Just how good (or bad) is the fossil record of dinosaurs?

August 28, 2015

Everyone is excited by discoveries of new dinosaurs – or indeed any new fossil species. But a key question for palaeontologists is 'just how good is the fossil record?' Do we know fifty per cent of the species of dinosaurs ...

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.