The sequences found in this family are similar to a region found in the beta-subunit of glucosidase II (Swiss:P14314), which is also known as protein kinase C substrate 80K-H (PRKCSH). The enzyme catalyses the sequential removal of two alpha-1,3-linked glucose residues in the second step of N-linked oligosaccharide processing [1]. The beta subunit is required for the solubility and stability of the heterodimeric enzyme, and is involved in retaining the enzyme within the endoplasmic reticulum [1]. The beta-subunit confers substrate specificity for di- and monoglucosylated glycans on the glucose-trimming activity of the alpha-subunit [2].

1: The heterodimeric structure of glucosidase II is required for its activity, solubility, and localization in vivo. Pelletier MF, Marcil A, Sevigny G, Jakob CA, Tessier DC, Chevet E, Menard R, Bergeron JJ, Thomas DY; Glycobiology 2000;10:815-827. PMID:10929008

2: Genetic analysis of glucosidase II beta-subunit in trimming of high-mannose-type glycans. Watanabe T, Totani K, Matsuo I, Maruyama J, Kitamoto K, Ito Y; Glycobiology. 2009;19:834-840. PMID:19395677