Defective B4GALT7 does not transfer Gal to xylosyl-unit of the tetrasaccharide linker

Stable Identifier
Reaction [transition]
Homo sapiens
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Beta 1,4 galactosyltransferase 7 (B4GALT7) adds galactose (Gal) to beta-xyloside in a beta-1,4-linkage creating the second unit in the tetrasaccharide linker sequence in proteoglycans, the precursor required for extension of glycosaminoglycan (GAG) chains (Almeida et al. 1999). Defects in B4GALT7 does not transfer Gal to the xylosyl-unit and therefore the tetrasaccharide linker sequence necessary for extension of the GAG chain cannot be completed, affecting GAG synthesis and causing Ehlers Danlos syndrome progeroid type (EDSP) (MIM:130070) (Okajima et al. 1999, Miyake et al. 2014). Mutations causing EDSP are A186D, L206P and R270C (Okajima et al. 1999, Almeida et al. 1999, Bui et al. 2010, Faiyaz-Ul-Haque et al. 2004).
Literature References
PubMed ID Title Journal Year
10506123 Molecular basis for the progeroid variant of Ehlers-Danlos syndrome. Identification and characterization of two mutations in galactosyltransferase I gene

Fukumoto, S, Urano, T, Okajima, T, Furukawa, K

J Biol Chem 1999
20691685 Molecular characterization of ?1,4-galactosyltransferase 7 genetic mutations linked to the progeroid form of Ehlers-Danlos syndrome (EDS)

Bui, C, Mulliert, G, Chabel, M, Talhaoui, I, Ouzzine, M, Coughtrie, MW, Fournel-Gigleux, S

FEBS Lett. 2010
15211654 A novel missense mutation in the galactosyltransferase-I (B4GALT7) gene in a family exhibiting facioskeletal anomalies and Ehlers-Danlos syndrome resembling the progeroid type

Faiyaz-Ul-Haque, M, Al-Thani, G, Zaidi, SH, Tsui, LC, Al-Mureikhi, MS, Teebi, AS, Kennedy, S, Al-Ali, M

Am. J. Med. Genet. A 2004
24443026 Ehlers-Danlos syndrome associated with glycosaminoglycan abnormalities

Miyake, N, Kosho, T, Matsumoto, N

Adv. Exp. Med. Biol. 2014
10473568 Cloning and expression of a proteoglycan UDP-galactose:beta-xylose beta1,4-galactosyltransferase I. A seventh member of the human beta4-galactosyltransferase gene family

Mandel, U, Almeida, R, Bennett, EP, Schwientek, T, Levery, SB, Clausen, H, Kresse, H

J Biol Chem 1999
Catalyst Activity

xylosylprotein 4-beta-galactosyltransferase activity of B4GALT7 mutants [Golgi membrane]

Normal reaction
Functional status

Loss of function of B4GALT7 mutants [Golgi membrane]

Name Identifier Synonyms
Ehlers-Danlos syndrome DOID:13359 Cutis hyperelastica, elastic skin
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