Our bodies recycle proteins, the fundamental building blocks
that enable cell growth and development. Proteins are made up of
a chain of amino acids, and scientists have known since the
1980s that first one in the chain determines the lifetime of a
protein. McGill researchers have finally discovered how the cell
identifies this first amino acid - and caught it on camera.
'There are lots of reasons cells recycle proteins - fasting,
which causes loss of muscle, growth and remodelling during
development, and normal turnover as old proteins are replaced to
make new ones,' explained lead researcher, Dr Kalle Gehring,
from McGill's Department of Biochemistry. 'One way that cells
decide which proteins to degrade is the presence of a signal
known as an N-degron at the start of the protein. By X-ray
crystallography, we discovered that the N-degron is recognised
by the UBR box, a component of the cells' recycling system.' The
powerful technique can pinpoint the exact location of atoms and
enabled the team to capture an