FIGURE 4.
The C tail of p38β inhibits autophosphorylation. A and B, premature stop codons were inserted into p38β generating p38β C-terminal truncation mutants p38βT341, p38βV345, p38βF348, and p38βK355. A, these proteins and p38βWT or an empty vector (emp) were transiently expressed in HEK293 cells with or without plasmids expressing MKK6EE. Cell lysates were prepared, and 30 μg of protein from each sample were separated by SDS-PAGE, blotted, and probed with the indicated antibodies. A summary of all chimeras tested is provided in Fig. 2B. B, 200 ng of recombinant p38 proteins were subjected to a kinase assay as described in the legend to Fig. 1.