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Beta adrenergic receptor kinase (also referred to as βARK or BARK) is a serine/threonine intracellular kinase. It is activated by PKA and its target is the beta adrenergic receptor. It is one method by which the cell will desensitize itself from epinephrine overstimulation. ==βARK Activation== * (steps 1) Upon stimulation of the Beta adrenergic receptor by epinephrine, Gs will be activated. * (steps 2 and 3) Gs alpha will then stimulate adenyl cyclase to make cAMP. * (steps 3 through 6) cAMP will then activate cAMP-dependent kinase (PKA), which, among other proteins that it acts on, will phosphorylate serine and threonine residues on βARK. * (step 7) βARK, itself a serine/threonine kinase, will then phosphorylate serine and threonine residues on the β-adrenergic receptor itself. * (step 8) This will facilitate Beta-arrestin's binding to the receptor. Additional stimulation by epinephrine will now be unable to activate Gs due to arrestin. Therefore, βARK is a negative feedback enzyme that will prevent overstimulation of the β-adrenergic receptor.〔〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Beta adrenergic receptor kinase」の詳細全文を読む スポンサード リンク
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