Autophosphorylation and ADP regulate the Ca²⁺-dependent interaction of recoverin with rhodopsin kinase

Recoverin is a 23 kDa myristoylated Ca²⁺-binding protein that inhibits rhodopsin kinase. We have used surface plasmon resonance to investigate the influences of Ca²⁺, myristoylation, and adenine nucleotides on the recoverin-rhodopsin kinase interaction. Our analyses confirmed that Ca²⁺ 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 Ca²⁺ 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.