Molecular cloning and characterization of a novel 3'-phosphoadenosine 5'-phosphosulfate transporter, PAPST2.
Sulfation is an important posttranslational modification associated with a variety of molecules. It requires the involvement of the high energy form of the universal sulfate donor, 3'-phosphoadenosine 5'-phosphosulfate (PAPS). Recently, we identified a PAPS transporter gene in both humans and Drosophila. Although human colonic epithelial tissues express many sulfated glycoconjugates, PAPST1 expression in the colon is trace. In the present study, we identified a novel human PAPS transporter gene that is closely related to human PAPST1. This gene, called PAPST2, is predominantly expressed in human colon tissues. The PAPST2 protein is localized on the Golgi apparatus in a manner similar to the PAPST1 protein. By using yeast expression studies, PAPST2 protein was shown to have PAPS transport activity with an apparent Km value of 2.2 microM, which is comparable with that of PAPST1 (0.8 microM). Overexpression of either the PAPST1 or PAPST2 gene increased PAPS transport activity in human colon cancer HCT116 cells. The RNA interference of the PAPST2 gene in the HCT116 cells significantly reduced the reactivity of G72 antibody directed against the sialyl 6-sulfo N-acetyllactosamine epitope and total sulfate incorporation into cellular proteins. These findings indicate that PAPST2 is a PAPS transporter gene involved in the synthesis of sulfated glycoconjugates in the colon.
Laboratory of Cell Biology, Department of Bioinformatics, Soka University, 1-236 Tangi-cho, Hachioji, Tokyo 192-8577, Japan.
Shin
S
Kamiyama
Norihiko
N
Sasaki
Emi
E
Goda
Kumiko
K
Ui-Tei
Kaoru
K
Saigo
Hisashi
H
Narimatsu
Yoshifumi
Y
Jigami
Reiji
R
Kannagi
Tatsuro
T
Irimura
Shoko
S
Nishihara
D000595:Amino Acid Sequence; D000818:Animals; D027321:Anion Transport Proteins / Q000378:metabolism / Q000502:physiology*; D001692:Biological Transport; D015152:Blotting, Northern; D015153:Blotting, Western; D045744:Cell Line, Tumor; D003001:Cloning, Molecular; D003106:Colon / Q000378:metabolism; D003110:Colonic Neoplasms / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004330:Drosophila; D000939:Epitopes / Q000737:chemistry; D005434:Flow Cytometry; D006001:Glycoconjugates / Q000737:chemistry; D006056:Golgi Apparatus / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D010957:Plasmids / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012441:Saccharomyces cerevisiae; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions; D000076988:Sulfate Transporters; D014018:Tissue Distribution; D014162:Transfection
D027321:Anion Transport Proteins; D018076:DNA, Complementary; D000939:Epitopes; D006001:Glycoconjugates; D026901:Membrane Transport Proteins; D034741:RNA, Small Interfering; C476248:SLC35B2 protein, human; C510864:SLC35B3 protein, human; D000076988:Sulfate Transporters