SLC35B3 Gene - Solute Carrier Family 35 Member B3 | Function, Mutations & Disease

SLC35B3 (Solute carrier family 35 member B3) is a protein-coding gene located on chromosome 6p21.1. It encodes a member of the solute carrier family 35 (SLC35) of nucleotide-sugar transporters, which are integral membrane proteins localized to the Golgi apparatus. These transporters facilitate the import of nucleotide sugars from the cytosol into the Golgi lumen, where they are used as substrates for glycosylation reactions. SLC35B3 is predicted to transport UDP-glucuronic acid (UDP-GlcA) and other nucleotide sugars, playing a role in proteoglycan and glycoprotein biosynthesis. The gene is expressed in multiple tissues, with highest levels in the liver and kidney. Mutations in SLC35B3 have been associated with congenital disorders of glycosylation (CDG) and other metabolic conditions.

Tissue Expression

Cell Line Expression

Hotspot Mutations

Mutation functional classification

• Nucleotide-sugar transport (Reactome: R-HSA-425407)

• Glycosaminoglycan metabolism (Reactome: R-HSA-1630316)

• Congenital disorders of glycosylation (KEGG: hsa00510)

The SLC35B3 protein (UniProt Q9Y2A2) is a 324-amino acid multi-pass transmembrane protein localized to the Golgi apparatus. It functions as a nucleotide-sugar transporter, specifically transporting UDP-glucuronic acid (UDP-GlcA) from the cytosol into the Golgi lumen. This transport is essential for the biosynthesis of glycosaminoglycans (e.g., heparan sulfate, chondroitin sulfate) and glycoproteins. The protein contains 10 predicted transmembrane helices and a conserved nucleotide-sugar transporter domain. Defects in SLC35B3 lead to congenital disorder of glycosylation type IIn (CDG-IIn), characterized by developmental delay, hypotonia, and coagulation abnormalities.