Regulatory subunit of glucosidase II that cleaves sequentially the 2 innermost alpha-1,3-linked glucose residues from the Glc(2)Man(9)GlcNAc(2) oligosaccharide precursor of immature glycoproteins (PubMed:27462106, PubMed:9148925). Required for efficient PKD1/Polycystin-1 biogenesis and trafficking to the plasma membrane of the primary cilia (PubMed:21685914). Glycan metabolism; N-glycan metabolism. Heterodimer of a catalytic alpha subunit (GANAB) and a beta subunit (PRKCSH) (PubMed:9148925, PubMed:27462106). Binds glycosylated PTPRC (PubMed:9148925). Expressed in kidney (at protein level). Knockout mice exhibit early embryonic lethality by 11.5 dpc. Conditional ubiquitous or kidney-specific knockdown results in polycystic liver and kidney phenotypes, respectively.