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Evidence for the functional similarity between tumour cell surface guanidinobenzoatase and tissue type plasminogen
F S Steven1, M M Griffin, S A Cederholm-Williams
1Department of Biochemistry and Molecular Biology, School of Biological Sciences, University of Manchester, U.K.
Abstract:
Tumour cells possess a cell surface protease referred to as guanidinobenzoatase (GB). The active centre of GB binds the fluorescent probe 9-amino acridine (9-AA) and this binding enables cells possessing active GB to be located by fluorescent microscopy. GB binding of 9-AA was inhibited by prior treatment of sections of tumour tissue with a specific polyclonal antibody recognising the tumour associated protease tissue plasminogen activator (t-PA). GB binding of 9-AA was also inhibited by prior treatment of sections of tumour tissues with PAI-I, a protein inhibitor of plasminogen activatory. We conclude from these studies and kinetic analyses that GB and t-PA are very similar both in structure and function.