Acts in the modification of cell walls via demethylesterification of cell wall pectin. Plays an important role in growth of pollen tubes in female floral tissues, possibly via enhancing the interaction between the pollen tube and female floral tissues by modification of the cell walls (PubMed:15659637). May be regulated by MYB80 during anther development and play a role in tapetum and pollen development (PubMed:21673079). [(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. Interacts with SBT6.1. Distributed in the whole pollen tube, including the plasma membrane and pollen tube wall (PubMed:15659637). Cleaved in the Golgi apparatus by SBT6.1 (S1P) after the Arg-Arg-Leu-Leu (RRLL) and Arg-Lys-Leu-Met (RKLM) motifs. This processing is required for extracellular targeting (PubMed:19144003). Expressed in pollen grains and pollen tubes. Expressed throughout silique development (PubMed:16622707). During anther development, expressed from stage 9 to stage 11 in late tapetum, and mature pollen grains (PubMed:21673079). The PMEI region may act as an autoinhibitory domain and prevent untimely PME activity during transport. The PMEI region is cleaved by SBT6.1 (S1P) in the Golgi apparatus prior to cell wall targeting. In the N-terminal section; belongs to the PMEI family. In the C-terminal section; belongs to the pectinesterase family. When tough is soft - Issue 106 of June 2009