Protein phosphatase 1 regulatory subunit 1A (PPP1R1A)

Protein phosphatase 1 regulatory subunit 1A (PPP1R1A), commonly known as **inhibitor-1 (I-1)**, is a cytosolic regulatory protein that controls the activity of protein phosphatase 1 (PP1), one of the major serine/threonine phosphatases in eukaryotic cells[2][3]. PPP1R1A itself is regulated by phosphorylation: when phosphorylated by cAMP-dependent protein kinase (PKA) at a key threonine residue, it becomes a potent inhibitor of PP1, thereby amplifying PKA signaling downstream of β-adrenergic stimulation. This mechanism is especially important in cardiac muscle, where PPP1R1A modulates contractility and rhythm by altering the phosphorylation state of key proteins such as phospholamban and troponin. PPP1R1A also plays roles in skeletal muscle metabolism, neuronal signaling, and potentially in diverse cellular responses through its ability to fine-tune PP1 substrate specificity and activity. Disrupted PPP1R1A signaling has been implicated in the pathogenesis of heart failure, neurological dysfunction, and other diseases, making it a candidate therapeutic target for interventions aimed at restoring phosphatase balance[2][3][1]. If more detailed drug information or disease links are required, refer to specialized pharmacology or cardiovascular research sources.

Other names

Protein phosphatase inhibitor 1I-1IPP1IPP-1inhibitor-1protein phosphatase inhibitor-1I1

Inhibition of PP1 catalytic activity by blocking substrate access when PPP1R1A is phosphorylated; indirect effects through modulation of PP1-dependent substrate dephosphorylation