Autophosphorylation of PC‐1 (Alkaline Phosphodiesterase I/Nucleotide Pyrophosphatase) and Analysis of the Active Site

Abstract

PC‐1 is an ecto‐enzyme possessing alkaline phosphodiesterase I (EC 3.1.4.1) and nucleotide pyrophosphatase (EC 3.6.1.9) activities. It has also been proposed to be an ecto‐protein kinase capable of phosphorylating itself as well as exogenous proteins. We have investigated the phosphorylation capability of PC‐1 and have developed a novel method for its detection and characterization based on autophosphorylation, which allows detection without the use of antibodies. When cells expressing membrane PC‐1 were held on ice with [γ‐32P]ATP, SDS/PAGE of whole cell lysates showed a single band which was PC‐1; this band was absent in cells not expressing PC‐1. Immunoprecipitates of soluble PC‐1 isolate..