B4GALT7

B4GALT7 Full Name

xylosylprotein beta1,4-galactosyltransferase, polypeptide 7 (galactosyltransferase I)

B4GALT7 Introduction

B4GALT7 (xylosylprotein beta-1,4-galactosyltransferase 7, also known as galactosyltransferase I or β4GalT7) is a key glycosyltransferase involved in the biosynthesis of proteoglycans, which are essential components of the extracellular matrix (ECM). For researchers investigating connective tissue disorders, ECM dysfunction, or glycosaminoglycan (GAG) metabolism, B4GALT7 represents an important molecular target because it regulates the formation of the linker region that connects GAG chains to core proteins. The B4GALT7-encoded enzyme catalyzes the transfer of a galactose residue from UDP-galactose to xylose-linked serine residues (Xyl-β-O-Ser) on proteoglycan core proteins, forming the second sugar residue of the conserved tetrasaccharide linker required for heparan sulfate and chondroitin sulfate biosynthesis. Through this role, B4GALT7 controls proper extracellular matrix organization, collagen-associated signaling, and tissue mechanical properties.

Alterations in B4GALT7 function have been strongly associated with congenital disorders of glycosaminoglycan biosynthesis, particularly spondylodysplastic Ehlers-Danlos syndrome type 1 (spEDS-B4GALT7). Loss-of-function mutations, including homozygous and compound heterozygous variants, impair proteoglycan linker formation and disrupt normal extracellular matrix assembly, leading to characteristic clinical manifestations such as short stature, skeletal abnormalities, joint hypermobility, skin fragility, and connective tissue defects. Studies of cellular and animal models have shown that complete loss of B4GALT7 activity can cause severe developmental defects, while hypomorphic variants with partially reduced enzyme activity better reproduce the variable severity observed in patients. These findings highlight the critical role of B4GALT7 in maintaining connective tissue integrity and demonstrate how defects in glycosylation pathways can contribute to human developmental diseases.

Beyond inherited connective tissue disorders, emerging evidence suggests that B4GALT7 may also participate in disease-related remodeling processes, including cancer progression. Recent studies have reported increased B4GALT7 expression in hepatocellular carcinoma tissues and cell models, where B4GALT7 suppression reduced tumor cell proliferation, migration, and invasion through regulatory pathways involving miR-338-3p, MMP2, and cell-cycle signaling networks. These findings indicate that B4GALT7 may function as a potential biomarker and therapeutic target in selected cancers while remaining primarily recognized as a regulator of extracellular matrix biology. Understanding B4GALT7-mediated glycosylation mechanisms provides valuable insights for developing new strategies targeting congenital connective tissue disorders, fibrosis-related conditions, and ECM-associated diseases.

Alternate Names for B4GALT7

B4galt7; xylosylprotein beta1,4-galactosyltransferase, polypeptide 7 (galactosyltransferase I); EDSP1; XGPT1; XGALT1; B4GALT7; xylosylprotein beta 1,4-galactosyltransferase, polypeptide 7

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• 1.Mizumoto S, Yamada S. Congenital Disorders of Deficiency in Glycosaminoglycan Biosynthesis. Front Genet. 2021, 12:717535.
  2.Syx D, et al.; Alterations in glycosaminoglycan biosynthesis associated with the Ehlers-Danlos syndromes. Am J Physiol Cell Physiol. 2022, 323(6):C1843-C1859.