Interaction of beta-endorphin and other opioid peptides with calmodulin
A highly purified preparation of calmodulin activated a calmodulin-deficient phosphodiesterase by more than 10-fold. This activation of phosphodiesterase by calmodulin was completely inhibited by two opioid peptides, beta-endorphin and dynorphin, at concentrations that had no appreciable effect on t...
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Veröffentlicht in: | Molecular pharmacology 1982-01, Vol.21 (1), p.86-91 |
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Sprache: | eng |
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Zusammenfassung: | A highly purified preparation of calmodulin activated a calmodulin-deficient phosphodiesterase by more than 10-fold. This
activation of phosphodiesterase by calmodulin was completely inhibited by two 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 calcium 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, calcium-dependent
manner with a dissociation constant of approximately 4.6 microM. There was substantially less binding of beta-endorphin to
troponin-C and little or no calcium-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. |
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ISSN: | 0026-895X 1521-0111 |