Protein phosphatase methylesterase 1

Protein phosphatase methylesterase 1 (PPME1, also PME-1) is a demethylase that catalyzes the removal of carboxymethyl modifications from protein substrates, including the protein phosphatase catalytic subunits PPP2CA and PPP2CB (UniProt: Q9Y570). By demethylating PPP2CA, PPME1 displaces the manganese cofactor and reduces enzymatic activity, thereby modulating phosphatase signaling.

PPME1 is a cytoplasmic protein with roles in protein phosphatase regulation. No specific tissue tropism or pathway associations are annotated in UniProt, and the protein has no curated disease associations in the UniProt record.

In Alzheimer's Disease, PPME1 is significantly upregulated in post-mortem AD brain tissue relative to age-matched controls (Chaparral AD proteomics). The mean log2 fold-change is +0.40, observed across one subcellular fraction in a TMT-labeled quantitative proteomics study of four fractions from human AD brain. This elevation may reflect altered phosphatase regulation as part of the AD pathological process.