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3  structures 1463  species 0  interactions 5784  sequences 58  architectures

Family: Nucleoside_tran (PF01733)

Summary: Nucleoside transporter

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This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.

Nucleoside transporter Provide feedback

This is a family of nucleoside transporters. In mammalian cells nucleoside transporters transport nucleoside across the plasma membrane and are essential for nucleotide synthesis via the salvage pathways for cells that lack their own de novo synthesis pathways [2]. Also in this family is mouse and human nucleolar protein HNP36 Q14542 a protein of unknown function; although it has been hypothesised to be a plasma membrane nucleoside transporter [2].

Literature references

  1. Crawford CR, Patel DH, Naeve C, Belt JA; , J Biol Chem 1998;273:5288-5293.: Cloning of the human equilibrative, nitrobenzylmercaptopurine riboside (NBMPR)-insensitive nucleoside transporter ei by functional expression in a transport-deficient cell line. PUBMED:9478986 EPMC:9478986

  2. Yao SY, Ng AM, Muzyka WR, Griffiths M, Cass CE, Baldwin SA, Young JD; , J Biol Chem 1997;272:28423-28430.: Molecular cloning and functional characterization of nitrobenzylthioinosine (NBMPR)-sensitive (es) and NBMPR-insensitive (ei) equilibrative nucleoside transporter proteins (rENT1 and rENT2) from rat tissues. PUBMED:9353301 EPMC:9353301

Internal database links

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR002259

Nucleosides are hydrophilic molecules and require specialised transport proteins for permeation of cell membranes. There are two types of nucleoside transport processes: equilibrative bidirectional processes driven by chemical gradients and inwardly directed concentrative processes driven by an electrochemical gradient [ PUBMED:10353709 ]. The two types of nucleoside transporters are classified into two families: the solute carrier (SLC) 29 and SLC28 families, corresponding to equilibrative and concentrative nucleoside transporters, respectively [ PUBMED:23506887 ].

Equilibrative nucleoside transporters (ENTs) are integral membrane proteins which enable the movement of hydrophilic nucleosides and nucleoside analogues down their concentration gradients across cell membranes. ENT family members have been identified in humans, mice, fish, tunicates, slime molds, and bacteria [ PUBMED:12446811 ].

Gene Ontology

The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.

Domain organisation

Below is a listing of the unique domain organisations or architectures in which this domain is found. More...

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Pfam Clan

This family is a member of clan MFS (CL0015), which has the following description:

The major facilitator superfamily (MFS) is one of the two largest families of membrane transporters found on Earth [1]. It is present ubiquitously in bacteria, archaea, and eukarya and includes members that can function by solute uniport, solute/cation symport, solute/cation antiport and/or solute/solute antiport with inwardly and/or outwardly directed polarity [1]. All permeases of the MFS possess either 12 or 14 transmembrane helices [1].

The clan contains the following 26 members:

Acatn ATG22 BT1 CLN3 DUF5690 Folate_carrier FPN1 LacY_symp MFS_1 MFS_1_like MFS_2 MFS_3 MFS_4 MFS_5 MFS_Mycoplasma Nodulin-like Nuc_H_symport Nucleoside_tran OATP PTR2 PUCC Sugar_tr TLC TRI12 UNC-93 UVB_sens_prot


We store a range of different sequence alignments for families. As well as the seed alignment from which the family is built, we provide the full alignment, generated by searching the sequence database (reference proteomes) using the family HMM. We also generate alignments using four representative proteomes (RP) sets and the UniProtKB sequence database. More...

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We make a range of alignments for each Pfam-A family. You can see a description of each above. You can view these alignments in various ways but please note that some types of alignment are never generated while others may not be available for all families, most commonly because the alignments are too large to handle.

Representative proteomes UniProt
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Representative proteomes UniProt

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You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.

HMM logo

HMM logos is one way of visualising profile HMMs. Logos provide a quick overview of the properties of an HMM in a graphical form. You can see a more detailed description of HMM logos and find out how you can interpret them here. More...


This page displays the phylogenetic tree for this family's seed alignment. We use FastTree to calculate neighbour join trees with a local bootstrap based on 100 resamples (shown next to the tree nodes). FastTree calculates approximately-maximum-likelihood phylogenetic trees from our seed alignment.

Note: You can also download the data file for the tree.

Curation and family details

This section shows the detailed information about the Pfam family. You can see the definitions of many of the terms in this section in the glossary and a fuller explanation of the scoring system that we use in the scores section of the help pages.

Curation View help on the curation process

Seed source: Pfam-B_2135 (release 4.1)
Previous IDs: none
Type: Family
Sequence Ontology: SO:0100021
Author: Bashton M , Bateman A
Number in seed: 7
Number in full: 5784
Average length of the domain: 247.30 aa
Average identity of full alignment: 23 %
Average coverage of the sequence by the domain: 63.73 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 61295632 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 29.8 29.8
Trusted cut-off 29.8 29.8
Noise cut-off 29.6 29.7
Model length: 309
Family (HMM) version: 21
Download: download the raw HMM for this family

Species distribution

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Colour assignments

Archea Archea Eukaryota Eukaryota
Bacteria Bacteria Other sequences Other sequences
Viruses Viruses Unclassified Unclassified
Viroids Viroids Unclassified sequence Unclassified sequence


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This visualisation provides a simple graphical representation of the distribution of this family across species. You can find the original interactive tree in the adjacent tab. More...

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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the Nucleoside_tran domain has been found. There are 3 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein sequence.

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AlphaFold Structure Predictions

The list of proteins below match this family and have AlphaFold predicted structures. Click on the protein accession to view the predicted structure.

Protein Predicted structure External Information
A0A0G2KJ38 View 3D Structure Click here
A0A0P0XCV7 View 3D Structure Click here
A0A0R0HG96 View 3D Structure Click here
A0A140LG26 View 3D Structure Click here
A0A1D6IF17 View 3D Structure Click here
A0A1D6IF21 View 3D Structure Click here
A0A1D6IF22 View 3D Structure Click here
A0A1D8PL42 View 3D Structure Click here
A0A2R8QJT6 View 3D Structure Click here
A1A4N1 View 3D Structure Click here
A1L272 View 3D Structure Click here
A4HUW2 View 3D Structure Click here
A4HVP9 View 3D Structure Click here
A4HWK9 View 3D Structure Click here
A4IDG6 View 3D Structure Click here
B4FVE5 View 3D Structure Click here
E1B6S1 View 3D Structure Click here
E9AGM5 View 3D Structure Click here
E9AGM6 View 3D Structure Click here
E9AGM7 View 3D Structure Click here
F1M2Y4 View 3D Structure Click here
F1QAM5 View 3D Structure Click here
F1R134 View 3D Structure Click here
G5EDJ3 View 3D Structure Click here
I1KF79 View 3D Structure Click here
I1L5J4 View 3D Structure Click here
I1LNZ3 View 3D Structure Click here
I1LZW8 View 3D Structure Click here
I1MU79 View 3D Structure Click here
K7M2T1 View 3D Structure Click here
K7MA00 View 3D Structure Click here
K7MA02 View 3D Structure Click here
K7N1G7 View 3D Structure Click here
O54698 View 3D Structure Click here
O54699 View 3D Structure Click here
P31381 View 3D Structure Click here
Q0D5J2 View 3D Structure Click here
Q14542 View 3D Structure Click here
Q19495 View 3D Structure Click here
Q21145 View 3D Structure Click here