the threonine residue phosphorylated in alpha s1-casein and accounting for most of the 32p incorporated into this protein by casein kinase 1a has been identified as thr-49 , which occurs in the sequence -ser ( p ) -glu-ser ( p ) -thr ( p* ) 49-glu-asp-gln- , whose two ser ( p ) residues are already phosphorylated in the native protein .
C0061472
glu
C0017797
gln