Keratan(2)-PG Keratan(1)-PG B4GALTs add another galactose to the chain Authored: Jassal, B, 2011-12-01 EC Number: 2.4.1.38 Edited: Jassal, B, 2011-12-01 Pubmed11588157 Pubmed11901181 Pubmed17021253 Pubmed1714903 Pubmed9597550 Reactome Database ID Release 432046265 Reactome, http://www.reactome.org ReactomeREACT_120893 Reviewed: D'Eustachio, P, 2012-03-28 The family of beta 4-galactosyltransferases (B4GALTs) is composed by at least six known members with different Km and acceptor specifities (Guo et al. 2001) and probably originated by duplication (Lo et al. 1998). They mediate the transfer of galactose to N-glycan structures, either to begin, or in this case, to elongate keratan chains. B4GALT1 is associated with Congenital Disorder of Glycosylation of type IId (Hansske et al. 2002), and is expressed as two splicing isoforms of which only one is localizated in the Golgi system (Lopez et al. 1991, Schaub et al. 2006).