INTERACTION OF BETA-ENDORPHIN AND OTHER OPIOID-PEPTIDES WITH CALMODULIN

  • 1 January 1982
    • journal article
    • research article
    • Vol. 21  (1) , 86-91
Abstract
A highly purified preparation of calmodulin activated a calmodulin-deficient phosphodiesterase by > 10-fold. This activation of phosphodiesterase by calmodulin was completely inhibited by 2 opioid peptides, .beta.-endorphin and dynorphin, at concentrations that had no appreciable effect on the basal phosphodiesterase activity. By contrast, similar concentrations of other structurally related peptides, including .alpha.-endorphin, (des-Tyr1)-.gamma.-endorphin, Leu-enkephalin, and Met-enkephalin, failed to block calmodulin''s activation of phosphodiesterase. The inhibition by .beta.-endorphin of calmodulin''s action was not reversed by Ca or by the opiate antagonist, naloxone, but was overcome by increasing the concentration of calmodulin. Equilibrium dialysis studies showed that 125I-labeled .beta.-endorphin bound directly to calmodulin in a saturable, Ca-dependent manner with a dissociation constant of .apprx. 4.5 .mu.M. There was substantially less binding of .beta.-endorphin to troponin C and little or no Ca-dependent binding of .beta.-endorphin to bovine serum albumin, lactalbumin or histone. This interaction of .beta.-endorphin with calmodulin was similar in several respects to the interaction of certain antipsychotic drugs to calmodulin and may explain certain of the peptide''s biochemical effects.

This publication has 18 references indexed in Scilit: