Autophosphorylation and ADP Regulate the Ca^(2+)-Dependent Interaction of Recoverin with Rhodopsin Kinase

Abstract

Recoverin is a 23 kDa myristoylated Ca^(2+)-binding protein that inhibits rhodopsin kinase. We have used surface plasmon resonance to investigate the influences of Ca^(2+), myristoylation, and adenine nucleotides on the recoverin−rhodopsin kinase interaction. Our analyses confirmed that Ca^(2+) is required for recoverin to bind RK. Myristoylation had little effect on the affinity of recoverin for the kinase, but it raised the K_(0.5) for Ca^(2+) from 150 nM for nonacylated recoverin to 400 nM for myristoylated recoverin. Finally, our studies also revealed two separate and previously unreported effects of adenine nucleotides on the recoverin−rhodopsin kinase binding. The interaction is weakened by autophosphorylation of the kinase, and it is strengthened by the presence of ADP.