Myristoylation-regulated direct interaction between calcium-bound calmodulin and N-terminal region of pp60v-src

J Mol Biol. 2004 Apr 16;338(1):169-80. doi: 10.1016/j.jmb.2004.02.041.


pp60v-src tyrosine protein kinase was suggested to interact with Ca2+-bound calmodulin (Ca2+/CaM) through the N-terminal region based on its structural similarities to CAP-23/NAP-22, a myristoylated neuron-specific protein, whose myristoyl group is essential for interaction with Ca2+/CaM; (1) the N terminus of pp60v-src is myristoylated like CAP-23/NAP-22; (2) both lysine residues are required for the myristoylation-dependent interaction and serine residues that are thought to regulate the interaction through the phosphorylations located in the N-terminal region of pp60v-src. To verify this possibility, we investigated the direct interaction between pp60v-src and Ca2+/CaM using a myristoylated peptide corresponding to the N-terminal region of pp60v-src. The binding assay indicated that only the myristoylated peptide binds to Ca2+/CaM, and the non-myristoylated peptide is not able to bind to Ca2+/CaM. Analyses of the binding kinetics revealed two independent reactions with the dissociation constants (KD) of 2.07 x 10(-9)M (KD1) and 3.93 x 10(-6)M (KD2), respectively. Two serine residues near the myristoyl moiety of the peptide (Ser2, Ser11) were phosphorylated by protein kinase C in vitro, and the phosphorylation drastically reduced the interaction. NMR experiments indicated that two molecules of the myristoylated peptide were bound around the hydrophobic clefts of a Ca2+/CaM molecule. The small-angle X-ray scattering analyses showed that the size of the peptide-Ca2+/CaM complex is 2-3A smaller than that of the known Ca2+/CaM-target molecule complexes. These results demonstrate clearly the direct interaction between pp60v-src and Ca2+/CaM in a novel manner different from that of known Ca2+/CaM, the target molecules, interactions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • Calcium / metabolism*
  • Calmodulin / chemistry
  • Calmodulin / metabolism*
  • Humans
  • Mass Spectrometry
  • Myristic Acid / metabolism*
  • Nuclear Magnetic Resonance, Biomolecular
  • Oncogene Protein pp60(v-src) / chemistry
  • Oncogene Protein pp60(v-src) / metabolism*
  • Peptide Fragments / chemistry
  • Peptide Fragments / metabolism*
  • Phosphorylation
  • Protein Binding
  • Protein Conformation
  • Protein Kinase C / pharmacology
  • X-Ray Diffraction


  • Calmodulin
  • Peptide Fragments
  • Myristic Acid
  • Oncogene Protein pp60(v-src)
  • Protein Kinase C
  • Calcium