The protein-tyrosine kinase substrate p36 is also a substrate for protein kinase C in vitro and in vivo.

p36, a major in vivo substrate of protein-tyrosine kinases, is shown to be phosphorylated at serine 25, a site very close to the major site of tyrosine phosphorylation by pp60v-src, tyrosine 23 (J. R. Glenney, Jr., and B. F. Tack, Proc. Natl. Acad. Sci. USA 82:7884-7888, 1985). We present evidence suggesting that protein kinase C mediates phosphorylation of serine 25.