Immunological studies on LATS-immunoglobulin by the reaction with staphylococcal protein A.

The reaction of LATS activity with Staphylococcal Protein A, a specific binding protein with the Fc part of human IgG(1), IgG(2) and Ig(4), was examined. When IgG(1), IgG(2) and Ig(4) subclasses were removed from LATS positive sera or LATS-IgG fractions by affinity chromatography on Protein A-Sepharose, LATS activity decreased. Almost all LATS activity was found in the fraction that reacted with Protein A. It is suggested that LATS has an expression of a very distinct immunoglobulin G structure, and that LATS activity is distributed mainly in the fraction containing IgG(1), Ig(2) and Ig(4) in LATS positive serum;