Phosphorylation of Arr2 by recombinant Drosophila
CaMKII1–275. A, CaMKII1–275
displays autonomous kinase activity. CaMKII1–275 was employed
for the phosphorylation of GST fusion containing the autocamtide sequence with
(lane 1) or without Ca2+/calmodulin (lane 3).
CaMKII1–275 also phosphorylates fusion protein containing a
short peptide of Arr2 encompassing Ser366 (lane 5).
Substitution of Ser366 with Ala completely eliminates the
phosphorylation (lane 6). Lanes 2 and 4 contain GST
alone. B, CaMKII1–275 phosphorylates the C terminus
of Arr2. GST fusion proteins containing the C terminus of Arr2 spanning
residues 305–400 (∼41 kDa in size, arrow) were
phosphorylated by recombinant CaMKII1–275 (lane 3).
Note that this Arr2 fusion protein forms dimers. For comparison,
phosphorylation of Arr2 peptide fusion is included in lane 1. In
contrast, GST alone (lane 2) and fusion proteins containing the N
terminus of INAD containing the first and second PDZ domains (∼74 kDa in
size) were not phosphorylated (lane 4). Protein size markers are
indicated on the left.