Equilibrative nucleoside transporter 4 (ENT4)

Equilibrative nucleoside transporter 4 (ENT4, also known as plasma membrane monoamine transporter [PMAT], SLC29A4) is a member of the SLC29 family of solute transporters characterized by 11 transmembrane domains and is primarily localized to the plasma membrane. Unlike other ENTs, ENT4 is distinct for its roles as both a pH-dependent adenosine transporter and a polyspecific organic cation/monoamine transporter. At neutral pH, it efficiently transports multiple biogenic amines, while under acidic conditions, such as those found in tissue ischemia or tumor microenvironments, it mediates the transport of adenosine and analogues like 2-chloroadenosine. ENT4 is transcriptionally upregulated in certain cancers (e.g., DSRCT), where it may support tumor growth by facilitating cellular adaptation to hypoxia and acidity. ENT4 plays important physiological roles in nucleoside salvage pathways, regulation of extracellular adenosine (with implications for ischemia protection), and neurotransmitter regulation.

Other names

Plasma membrane monoamine transporterPMATSLC29A4

Facilitation/diffusion of nucleosides and monoamines across the plasma membrane down their concentration gradient (equilibrative, pH-dependent for adenosine transport). At neutral pH, acts as a polyspecific organic cation/monoamine transporter; at acidic pH, acts as an adenosine/adenosine analogue transporter