Addition of the first mannose to the N-glycan precursor by ALG13/14 A mannose is added to the N-glycan precursor via a beta-1,4 linkage. The reaction is catalyzed by ALG1 (Takahashi T et al, 2000). Defects in ALG1 lead to congenital disorder of glycosylation type 1K (CDG1K) (Schwarz M et al, 2004; Kranz C et al, 2004; Grubenmann CE et al, 2004). Authored: Dall'Olio, GM, 2009-11-10 EC Number: 2.4.1.142 Edited: Jassal, B, 2009-11-10 Pubmed10704531 Pubmed14709599 Pubmed14973778 Pubmed14973782 Reactome Database ID Release 43446218 Reactome, http://www.reactome.org ReactomeREACT_22214 Reviewed: Gagneux, P, 2010-04-16