| In the macrophage, control of actin dynamics is achieved in part by the
participation of Cap G, a protein discovered in this laboratory. This
calcium-sensitive actin filament capping protein can regulate the assembly
and disasssembly of actin-cytoskeleton during macrophage movement. CapG
binds the barbed or rapid growing end of actin filaments in the presence of
calcium. When the calcium concentration is lowered CapG dissociates from the
barbed end allowing actin assembly to again occur. PCR generated point
mutations have been made in the molecule to assess the relationship between
primary structure and function. We have created gain-of-function mutations
that convert CapG from a capping to a capping and severing protein addition.
In collaboration with Dr. Stephen Almo (Albert Einstein University) we are
presently crystallizing wild-type and the severing mutant and have begun to
map their tertiary structure.
|
|
Wild-type (left) and CapG-null
neutrophils crawling toward a chemotactic gradient. Note the lack of shape
change in the CapG-null cells. |
