InterPro domain: IPR026051

ALG1 (Asparagine-linked glycosylation protein 1) proteins participate in the formation of the lipid-linked precursor oligosaccharide for N-glycosylation. They are also involved in assembling the dolichol-pyrophosphate-GlcNAc(2)-Man5 intermediate on the cytoplasmic surface of the ER [ 1 , 2 ].

Defects in human ALG1 are the cause of congenital disorder of glycosylation type 1K (CDG1K). CDGs are characterised by under-glycosylated serum proteins. These multisystem disorders present with a wide variety of clinical features, such as disorders of the nervous system development, psychomotor retardation, dysmorphic features, hypotonia, coagulation disorders, and immunodeficiency. [ 3 , 4 , 5 ].

Glycosylation and growth of Alg1-deficient PRY56 yeast cells, showing a temperature-sensitive phenotype, could be restored by the human wild-type allele [ 6 ].

1. Cloning of the human cDNA which can complement the defect of the yeast mannosyltransferase I-deficient mutant alg 1. Glycobiology 10, 321-7
2. Physical interactions between the Alg1, Alg2, and Alg11 mannosyltransferases of the endoplasmic reticulum. Glycobiology 14, 559-70
3. Deficiency of GDP-Man:GlcNAc2-PP-dolichol mannosyltransferase causes congenital disorder of glycosylation type Ik. Am. J. Hum. Genet. 74, 472-81
4. Congenital disorder of glycosylation type Ik (CDG-Ik): a defect of mannosyltransferase I. Am. J. Hum. Genet. 74, 545-51
5. Deficiency of the first mannosylation step in the N-glycosylation pathway causes congenital disorder of glycosylation type Ik. Hum. Mol. Genet. 13, 535-42