CONCLUSIONS
This study of the cysteine accessibility in the keratins and KAPs of the
wool cortex has revealed the following:
- Repeatably accessible (non-random) cysteines found in the head and
tail domains in the type I and II keratins are likely to be on the
surface of the intermediate filament and, hence, available for
interactions with KAPs.
- Two accessible cysteines were found in coil 2 in the type I keratin
K31 which are potentially involved in crosslinks with other keratins
in the filament. One cysteine in
position 2-90 in a type I keratin is possibly in a good orientation to
be involved in a crosslink with another cysteine also at position 2-90
in a second type I keratin, while a second cysteine at position 2-132
in a type I keratin has also been identified as the site of another
potential keratin-keratin crosslink.
- One accessible cysteine at position T-5 in the tail domain of K83 and
K86 is in a position where it could be involved in crosslinking with a
cysteine close to the C-terminus of the head domain of type I
keratins.
- Cysteines at positions L1-9 of K34 and 1B-87 of K31 are most probably
linked via a disulfide interaction.
- The ready accessibility of the cysteines involved in disulfide
interactions between keratins in the intermediate filament point to
how oxidative stress on the fiber brought on by environmental factors
has the potential to affect the integrity of the filament itself.
- The bulk of the most readily accessible cysteines in the KAPs were
found close to either the N- or C-terminal domains in these proteins.