solute carrier family 28 member 3 (concentrative Na+-nucleoside cotransporter 3, hCNT3, SLC28A3, CNT3)

Function

• Na+-dependent, pyrimidine- & purine-selective involved in homeostasis of endogenous nucleosides
• exhibits transport characteristics of nucleoside transport system cib or N3 subtype (N3/cib) (with marked transport of both thymidine & inosine)
• employs a 2:1 Na+/nucleoside ratio
• also able to transport gemcitabine, zidovudine (AZT), ribavirin & 3-deazauridine

Kinetic parameters:

• KM=21.6 uM for uridine
• KM=15.4 uM for cytidine
• KM=21.2 uM for thymidine
• KM=15.1 uM for adenosine
• KM=43 uM for guanosine
• KM=52.5 uM for inosine
• Vmax=25.8 pmol/min/mg enzyme for uridine uptake
• Vmax=32.8 pmol/min/mg enzyme for cytidine uptake
• Vmax=24.2 pmol/min/mg enzyme for thymidine uptake
• Vmax=30.4 pmol/min/mg enzyme for adenosine uptake
• Vmax=51.4 pmol/min/mg enzyme for guanosine uptake
• Vmax=44.8 pmol/min/mg enzyme for inosine uptake

Structure

belongs to the SLC28A transporter family

Compartment

membrane (potential)

Expression

• expressed in pancreas, bone marrow, trachea, mammary gland, liver, prostate, & regions of intestine, brain, lung, placenta, testis, kidney, & heart
• up-regulated by phorbol myristate acetate (PMA), in HL-60 cells

More general terms

• transmembrane 13c protein
• solute carrier family 28 (SLC28, SLC28A)

Database

• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:6407
• OMIM: https://mirror.omim.org/entry/608269
• UniProt: http://www.uniprot.org/uniprot/Q9HAS3.html