Protein Phosphatase 1, Regulatory Subunit 14D (PPP1R14D)

The deduced 145-amino acid protein contains an N-terminal consensus PP1-binding motif (KKVHW) and numerous potential phosphorylation sites. RT-PCR detected GPBI1 expression in colon, intestine, kidney, and cerebral cortex, but not in other tissues examined. Mouse tissues showed a similar expression profile, but also included a testis-specific splice variant encoding a putative membrane-bound isoform.PKC-phosphorylated GBPI1 inhibited the activity of rabbit muscle Pp1-alpha (PPP1CA) and enhanced the activity of bovine kidney Pp2a1 (PPP2CA) in vitro. Nonphosphorylated and PKA-phosphorylated GBPI1 were inactive in these assays, and PKC-phosphorylated GBPI1 that was subsequently phosphorylated by PKA lost its ability to inhibit Pp1-alpha.