Protein complex studies on calmodulin - GAP-43 (neuromodulin)

Abstract

Calmodulin (CaM) is a ubiquitous Ca2+-binding protein found in all eukaryotic cells. It interacts with a wide variety of proteins and modulates their functions. In low intracellular Ca2+ concentration, Ca2+-free CaM (apoCaM) interacts with proteins containing IQ motif. GAP-43 (Neuromodulin) is a neuron specific growth-associated protein containing IQ-motif as its CaM-binding domain. It is considered to be a major determinant of synaptic development and plasticity, and has been implicated in molecular mechanisms underlying learning and memory. PKC phosphorylation has important effects on the interaction between CaM and GAP-43.CaM and a GAP-43 truncate (GAP-43t) were overexpressed and purified. Protein complex of apoCaM and GAP-43t was obtained by GTA crosslinking and identified by SDS-PAGE analysis. This protein complex provides a new approach to the studies on both the CaM a?? GAP-43 interaction and the apoCaM a?? IQ motif interaction. Further studies on the protein complex will provide significant insights into both interactions.