EFFECT OF PHENYLALANINE AND ALPHA-METHYLPHENYLALANINE ON IN-VITRO INCORPORATION OF P-32 INTO CYTOSKELETAL CEREBRAL PROTEINS

We studied the effects of L-phenylalanine and alpha-methylphenylalanine on P-32 in vitro incorporation into cytoskeletal proteins from cerebral cortex of 17-day-old rats. Slices of cerebral cortex were incubated in the absence or presence of increasing concentrations of L-phenylalanine, alpha-methylphenylalanine or L-phenylalanine plus alpha-methylphenylalanine for 1 h. The cytoskeletal fraction obtained from slices was incubated in the presence of the same drugs and the P-32 in vitro incorporation into cytoskeletal proteins was measured. Addition of alpha-methylphenylalanine did not change P-32 in vitro incorporation into the cytoskeletal proteins, but phenylalanine decreased the in vitro phosphorylation of beta tubulin. Furthermore, addition of L-phenylalanine plus alpha-methylphenylalanine decreased the in vitro phosphorylation of both 160 kDa neurofilaments and alpha-tubulin.