Patent ID: 7255999

Claim:
A method for determining the presence or absence of one or more target polypeptides in a sample suspected of containing the target polypeptides, the method comprising the steps of: (a) mixing the sample with (i) a class-specific reagent comprising, a cleavage-inducing moiety attached a first binding agent that specifically bind a post-translational modification on the one or more target polypeptides, and (ii) one or more electrophoretic probes, each of which is attached to a first binding moiety that specifically binds one of the target polypeptides and one or more electrophoretic tags each attached thereto by a cleavable linkage, under conditions that permit the class-specific reagent and the one or more electrophoretic probes to bind to the one or more target polypeptides, and which brings the cleavage inducing moiety within an effective proximity to a cleavable linkage of said one or more electrophoretic probe; (b) cleaving the cleavable linkages(s) of any of the one or more electrophoretic probes within the effective proximity of the cleavage-inducing moiety so that one or more electrophoretic tags are released wherein cleaving is by the cleavage-inducing moiety; and (c) determining the presence or absence of the one or more target polypeptides based on the presence or absence of the released electrophoretic tags.