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]. Mutations in the gene coding for PRKCSH have been found to be involved in the development of autosomal dominant polycystic liver disease (ADPLD), but the precise role the protein has in the pathogenesis of this disease is unknown [2]. This family also includes an ER sensor for misfolded glycoproteins and is therefore likely to be a generic sugar binding domain.

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: Mutations in PRKCSH cause isolated autosomal dominant polycystic liver disease. Li A, Davila S, Furu L, Qian Q, Tian X, Kamath PS, King BF, Torres VE, Somlo S; Am J Hum Genet 2003;72:691-703. PMID:12529853