SOLUTE CARRIER FAMILY 35 (3-PRIME-PHOSPHOADENOSINE 5-PRIME-PHOSPHOSULFATE TRANSPORTER), MEMBER B3; SLC35B3

Alternative titles; symbols

• 3-PRIME-PHOSPHOADENOSINE 5-PRIME-PHOSPHOSULFATE TRANSPORTER; PAPST2
• PAPS TRANSPORTER 2

HGNC Approved Gene Symbol: SLC35B3

Cytogenetic location: 6p24.3 Genomic coordinates (GRCh38): 6:8,411,434-8,435,566 (from NCBI)

▼ Description
Sulfation of a variety of molecules, including glycoproteins, proteoglycans, and glycolipids, requires 3-prime phosphoadenosine 5-prime phosphosulfate (PAPS), a high-energy form of the universal sulfate donor. SLC35B3 translocates PAPS from the cytosol or nucleus, where it is synthesized, to the Golgi lumen for use (Kamiyama et al., 2006).

▼ Cloning and Expression
By searching databases for genes similar to UGTREL1 (SLC35B1; 610790), followed by PCR of a colon cDNA library, Kamiyama et al. (2006) cloned SLC35B3, which they called PAPST2. The deduced 401-amino acid protein has a calculated molecular mass of 44.6 kD. It is a type III transmembrane protein with 9 transmembrane domains and 8 potential N-glycosylation sites. Epitope-tagged PAPST2 localized to Golgi in a transfected human colon cancer cell line. Northern blot analysis detected a 2-kb PAPST2 transcript in colon cancer cell lines and normal colon tissue. Real-time PCR detected variable expression of PAPST2 in all tissues examined, with highest levels in colon, followed by pancreas.

▼ Gene Function
Using yeast expression studies, Kamiyama et al. (2006) showed that PAPST2 had PAPS transport activity with kinetics comparable to those of PAPST1 (SLC35B2; 610788). Overexpression of PAPST2 or PAPST1 increased PAPS transport activity in human colon cancer HCT116 cells. RNA interference of PAPST2 in HCT116 cells significantly reduced levels of the sialyl 6-sulfo N-acetyllactosamine epitope and total sulfate incorporation into cellular proteins.

▼ Gene Structure
Kamiyama et al. (2006) determined that the SLC35B3 gene contains 11 exons.

▼ Mapping
By genomic sequence analysis, Kamiyama et al. (2006) mapped the SLC35B3 gene to chromosome 6p24.3.