Post-translational phosphorylation affects the IgE binding capacity of caseins

IgE response specific to those molecular regions of casein that contain a m ajor phosphorylation site was analyzed using native and modified caseins an d derived peptides. This study included (i) the naturally occurring common variants A1 and A from beta- and alpha s2-caseins, respectively, which were purified in the native form and then dephosphorylated, (ii) a purified rar e variant D of alpha s2-casein which lacks one major phosphorylation site, and (iii) the native and dephosphorylated tryptic fragment f(1-25) from bet a-casein. Direct and indirect ELISA using sera from patients allergic to mi lk showed that the IgE response to caseins is affected by modifying or elim inating the major phosphorylation site. (C) 2000 Federation of European Bio chemical Societies.