| Method |
"A simple calculation, the difference between the experimental
measurements of the numbers of Arp2/3 complex
(ARPC5) and capping protein (Acp2p) molecules in a patch
(Figure 6D in Sirotkin et al., 2010), established that patches
could contain up to 140 free barbed ends, but the simulations
showed that actual number is much less, because at
every point in time, a large fraction of the Arp2/3 complex
has not initiated a branch (Figure 3C). In fact, a rough
estimate showed that only eight barbed ends are required to
account for the maximum polymerization rate of about 2000
subunits per second (i.e., eight ends×22µM actin monomers×12µM^-1×sec^-1)." |