The team was co-led by Jacek Gaertig, associate professor of cellular biology at UGA, and Bernard Edd of National Center for Scientific Research (CNRS) in France.
Cells have an internal highway system made of fibers called microtubules. Specialized motor proteins slide along these fibers, carrying organelles and other materials to the places they need to go. But how do motor proteins know where to take their cargoes?
The researchers identified a new enzyme group that attaches an unusual molecular tag to a component of the cell's microtubular highway system. The tag is attached to a localized region of a microtubule and may act like a road sign on the Interstate, directing motor proteins to take the "proper exit" to the nucleus or the cell membrane.
"We've known for more than a decade that strings of glutamic acid (an amino acid) are sometimes attached to the side of a protein called tubulin," said Gaertig, one of the senior co-authors on the paper. Tubulin is a component of microtubules. "This modification occurs in all cells but is abundant in neurons in the brain."
Few other proteins are modified in this way. But investigating what the modification does and how it works has been difficult until now.
The authors have identified a new group of enzymes -- called polyglutamylases -- that attach glutamic acid chains of varying length and branching patterns.
Because the enzyme complex is active only for a short window during development in mice, it took a "biochemical tour de force" by collaborators in Fr
Contact: Kim Carlyle
University of Georgia