COMPARATIVE-ANALYSIS OF BETA-ADRENERGIC-RECEPTOR KINASE AND BETA-ARRESTIN MESSENGER-RNA EXPRESSION IN HUMAN-CELLS

Receptor phosphorylation is a key step in the process of rapid desensitization. Beta-Adrenergic receptor kinase is a specific receptor kinase that is known to phosphorylate and induce desensitization of several G-coupled synaptic receptors only when they are occupied by their agonists. We recently cloned human betaARK cDNA and reported high levels of betaARK expression in human peripheral blood leukocytes, also providing the first evidence for its possible functional role in these cells. Complete homologous receptor desensitization by betaARK requires an additional cytosolic factor, called beta-arrestin. In the present study, we have cloned a 212 bp fragment of the human beta-arrestin cDNA to perform a comparative analysis of betaARK and beta-arrestin mRNA expression in various human cell types. We found that also beta-arrestin mRNA is abundant in non-innervated tissues and cells. The fact that the entire machinery for G-coupled receptor desensitization is highly expressed in these cells further supports the idea that betaARK may regulate non-synaptic as well as synaptic receptors.