cassette components?

[Samuel J. Rulli, Jr]

Can anyone give me the significance/use for the following components in
a plasmid, they are downstream of the promoter, and upstream of the
MCS- thioredoxin coding sequence, enterokinase recognition site, His6
coding sequence.

Thanks in advance


The enterkinase site is a recognition site in the translated protein for the
protease enterkinase, this small peptide sequence will allow the his6
sequence to be removed.  The his6 sequence is 6 histidines that will allow
the expressed protein to be purified on either nickel or cobalt resins,
since histidines at a certain pH have high affinity for metals. (especially
6 his in a sequence).  The thioredioxin sequence???? I'm not sure.