Abstract: The present invention relates to novel organic compounds, to methods for their preparation, to compositions containing them, to their use for treatment of human and animal disorders, to their use for purification of proteins or glycoproteins, and to their use in diagnosis. The invention relates to modulation of the activity of molecules with phospho-tyrosine recognition units, including protein tyrosine phosphatases (PTPases) and proteins with Src-homology-2 domains, in in vitro systems, microorganisms, eukaryotic cells, whole animals and human beings. The novel organic compounds are compounds of formula (I)(L).sub.n --Ar.sub.1 --R.sub.1 --A (I)wherein(L).sub.n, n, Ar.sub.1, R.sub.1 and A are as defined in the application.

Abstract: A novel protein tyrosine phosphatase designated PTP-S31 and its subfamily are identified, as are nucleic acid molecule coding therefor. Included in this family are PTP-S31 proteins or glycoproteins having one, two, or three identified amino acid changes in previously defined consensus sequences in the catalytic phosphatase domains of known protein tyrosine phosphatases. The PTP-S31 proteins or glycoproteins may be produced by recombinant means. Antibodies to PTP-S31 proteins or glycoproteins and nucleic acid constructs coding therefor, and methods for screening molecules which can bind to PTP-S31 proteins or glycoproteins and inhibit or stimulate their enzymatic activity, are provided.