|
Most
members of the ADF/cofilin family are pH sensitive in their
interaction with F-actin. This was first reported by
Yonezawa (Yonezawa
et al, 1985).
In considering the pH dependency of protein protein interaction
one invariably focuses on histidines as they uniquely have pKa
values within the physiological range. However, when we
consider the pH dependency of the interaction between
ADF/cofilins and F-actin it is obvious that the histidines that
may be suspected of being at this interface are not conserved
between the various species.
Actophorin
is not pH sensitive as typical members of the group are.
Actophorin behaves with respect to F-actin as these other
members do at pH 6.5 at all pH values tested (pH6.5 - 8.0) in
other words actophorin binds F-actin or actin aggregates at pH
8.0 whereas other members of the group bind G-actin exclusively
at this pH value. The molecular mechanism for these
differences are not presently known. The plant ADF/cofilin
ZmADF3 has been shown to be pH sensitive but the threshold pH
value is shifted
|
