Secret Of Heartbeat Protein Unravelled

Scientists in the US have solved the structure of a critical piece of protein used to keep hearts beating that they say will help treat cardiac or neurological diseases. Biologist Dale Mierke and other researchers at Brown University have solved the structure of synapse-associated protein 97 (SAP97) found in abundance in the heart and head, reports university website www.brown.edu.

This protein is believed to play a role in everything from cardiac contractions to memory creation.

SAP97 is found mainly in the central nervous system and is known as a "scaffolding" protein. In this role, it serves as a sort of tether, grabbing proteins inside the cell critical to nerve signalling and keeping them close to N-methyl-D-asparate (NMDA) receptors at the cell surface.

NMDA receptors help usher in a neurotransmitter called glutamate that is essential for learning and memory and also plays a role in drug addiction. A similar scaffolding mechanism is at work in the heart, where it affects basic functions, including the heartbeat.

SAP97 is a complex protein made up of five "domains" similar to a train comprising an engine and four boxcars. In their experiments, Mierke and other researchers focused on the engine.

This domain, known as PDZ1, is where the protein links to NMDA receptors. The team used high-resolution nuclear magnetic resonance spectroscopy to solve the structure of PDZ1, as well as a small portion of the receptor to which it binds.

Mierke said knowing how a piece of SAP97 is built is an important step. Now that part of the protein's structure is solved, scientists can create a molecule to disable it. That, in turn, will allow them to fully understand SAP97's role in the body.

And that will point drug makers to targets for developing new ways to treat cardiac or neurological diseases, he said.

Indo-Asian News Service