PEX5 and Ubiquitin Dynamics on Mammalian Peroxisome Membranes
Figure 4
Cooperatively coupled cargo translocation.
(A) Cytosolic PEX5-cargo concentration vs. PEX5 cargo addition rate, . The dashed black line is the measured cytosolic PEX5 concentration of
[43]. Inset shows the fraction of importomers that are fully occupied by PEX5 vs. PEX5 cargo addition rate, with five PEX5 sites per importomer and cooperative coupling. (B) peroxisomal PEX5 fraction vs.
for cooperatively coupled cargo translocation. (C) Fraction of peroxisomal PEX5 that is ubiquitinated vs.
. (D) ubiquitin per peroxisome vs.
. A characteristic decrease of ubiquitination with
is seen that is largely independent of the number of binding sites
. Different number of binding sites per importomer are shown from
(red circles) to
(green diamonds), as shown in the legend in (B). Cooperative coupling cannot function with
, so that is not shown. Subsequent figures use
(blue squares). Note that the vertical scale of ubiquitin per peroxisome in (D) is much larger than in Fig. 3.