A monoclonal antibody which identifies the autophosphorylation domain of autophosphorylating protein kinase 500

Abstract

Autophosphorylating protein kinase 500 is a serine protein kinase expressed progressively with the steps of cellular transformation, approaching levels from 50- to 100-fold in the terminal stages of malignancy. The enzyme possesses a sharply restricted range of substrates: itself and a ribosomal protein with a molecular weight of 31,000 (S6). We report here on the characterization of a monoclonal antibody directed against the autophosphorylation domain of AUT-PK 500. The specificity of the antibody is evidenced by blockage of the enzyme phosphorylation without interfering with the native S6 or synthetic octapeptide (S6-1) serine residue phosphorylations. This represents an important step in identifying a probe that can be used to explore the structure and potential function of AUT-PK 500 in cellular transformation.