Cleaves sequentially the 2 innermost alpha-1,3-linked glucose residues from the Glc(2)Man(9)GlcNAc(2) oligosaccharide precursor of immature glycoproteins (By similarity). Essential for stable accumulation of the receptor EFR that determines the specific perception of bacterial elongation factor Tu (EF-Tu), a potent elicitor of the defense response to pathogen-associated molecular patterns (PAMPs). Required for sustained activation of EFR-mediated signaling, but not receptor FLS2-mediated signaling elicited by the bacterial flagellin flg22. Hydrolysis of terminal (1->3)-alpha-D-glucosidic links in (1->3)-alpha-D-glucans. Glycan metabolism; N-glycan metabolism. Heterodimer of a catalytic alpha subunit (PSL5) and a beta subunit (PSL4). Expressed in roots, rosette leaves, leaf blades, mature stems, cauline leaves, flower buds, flowers and siliques. No visible phenotype under normal growth conditions (permissive temperature of 21 degrees Celsius), but mutant plants have a temperature-sensitive phenotype (when transferred to 30 degrees Celsius) showing radially swollen roots and reduction in cellulose production. Belongs to the glycosyl hydrolase 31 family.