amined the expression of this antigen in human platelets
treated with PDI, ERp5, and ERp57, alone and in combination
by flow cytometry. We did not observe expression of the
active conformer upon incubation of PDI, ERp5, ERp57, or a
mixture of PDI+ERp5+ERp57 (Fig. 7). Under the conditions
studied, b3 does not appear to be a substrate of these thiol
isomerases. However, these thiol isomerases all bind to b3.
Therefore, it would appear that the pathway to b3 activation
involves these thiol isomerases, but they do not directly alter
the b3 conformation to express the structure associated with
integrin activation.