Probably an alpha-glucosidase, it has no alpha-amylase function. (Microbial infection) Serves as the larval receptor for Lysinibacillus sphaericus BinB toxin (Ref.2). Hydrolysis of terminal, non-reducing (1->4)-linked alpha-D-glucose residues with release of alpha-D-glucose. (Microbial infection) Binds to L.sphaericus BinB subunit of the binary toxin BinAB. In 4th-instar larvae produced in the brush border membranes of the gastric caeca and the posterior stomach cells (at protein level). Expressed in 4th-instar larval midgut, in the brush border membranes of the gastric cesum and the posterior stomach cells (at protein level). In mosquito strain GEO, which is 10(5)-fold more resistant to L.sphaericus than wild-type, a premature stop codon at Leu-569 leads to loss of the probable GPI anchor and disrupts the correct subcellular location. Restoration of Leu-269 rescues the subcellular location and binary Bin toxin binding to transfected Sf9 cells in culture (PubMed:11983886). Belongs to the glycosyl hydrolase 13 family.