Acts in the modification of cell walls via demethylesterification of cell wall pectin. [(1->4)-alpha-D-galacturonosyl methyl ester](n) + n H2O = [(1->4)-alpha-D-galacturonosyl](n) + n H(+) + n methanol Glycan metabolism; pectin degradation; 2-dehydro-3-deoxy-D-gluconate from pectin: step 1/5. Expressed at high levels in flower buds, shoots and young leaves, and at lower levels in young fruit, young bark and juice vesicles. Not expressed at significant levels in leaf abscission zones following ethylene treatment or in mature leaves. In fruit abscission zones, expression was initially undetectable but increased markedly following ethylene treatment. By ethylene. The PMEI region may act as an autoinhibitory domain and prevent untimely PME activity during transport. In the N-terminal section; belongs to the PMEI family. In the C-terminal section; belongs to the pectinesterase family.