| Furthermore , chimeric analysis with p38beta ( which does not bind to TAB 1 ) revealed a previously unidentified locus of p38alpha comprising Thr 218 and Ile 275 that is essential for specific binding of p38alpha to TAB 1 . ^^^ Converting either of these residues to the corresponding amino acid of p38beta abolishes p38alpha interaction with TAB 1 . ^^^ |