The knottin scaffold is considered as a useful stabilizing framework
to deliver bioactive peptide drugs.
For intracellular targets, it may be necessary for the knottin-based drug
to enter cells.
Internalization of MCoTI-II
It has been shown that the cyclic knottin MCoTI-II is internalized into
mammalian cells by macropynocytose.
[Grenwood et al., 2007].
As a consequence MCoTI-II may have the potential to transport bioactivities
to intracellular targets.
Internalization of PA1b
The toxin PA1b from pea is lethal for certain insects.
It has been shown that PA1b is internalized into insect cells sf9 by binding to
a high-affinity site. The mecanisms leading to cell death remain to be determined.
Mammalian cells are insensitive to the toxin.
[Rahioui et al., 2007].