Atypical Solute Carrier Families (Atypical SLCs) are novel plausible secondary active or facilitative transporter proteins that share ancestral background with the known solute carrier families (SLCs). However, they have not been assigned a name according to the SLC root system, or been classified into any of the existing SLC families.

Atypical major facilitator superfamily transport families

Most atypical SLCs are

families Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Ideal ...

within the

major facilitator superfamily The major facilitator superfamily (MFS) is a superfamily of membrane transport proteins that facilitate movement of small solutes across cell membranes in response to chemiosmotic gradients. Function The major facilitator superfamily (MFS) are ...

(MFS). These atypical SLCs are plausible secondary active or facilitative transporter proteins that share ancestry with the known solute carriers. They are, however, not named according to the SLC root system, or classified into any of the existing SLC families. ATMFs are categorised based on their sequence similarity and phylogenetic closeness. Some Atypical SLC of MFS type are:

OCA2 P protein, also known as melanocyte-specific transporter protein or pink-eyed dilution protein homolog, is a protein that in humans is encoded by the oculocutaneous albinism II (''OCA2'') gene. The P protein is believed to be an integral membrane ...

CLN3 G1/S-specific cyclin Cln3 is a protein that is encoded by the ''CLN3'' gene. The Cln3 protein is a budding yeast G1 cyclin that controls the timing of ''Start'', the point of commitment to a mitotic cell cycle. It is an upstream regulator of t ...

, SPNS1, SPNS2, SPNS3, SV2A, SV2B, SV2C, SVOP, SVOPL, MFSD1,

MFSD2A Major facilitator superfamily domain-containing protein 2 (MFSD2 or MFSD2A) -- also known as sodium-dependent lysophosphatidylcholine symporter 1 -- is a protein that in humans is encoded by the ''MFSD2A'' gene. MFSD2A is a membrane transport pr ...

, MFSD2B,

MFSD3 Major facilitator superfamily domain containing 3 (MFSD3) is a protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organ ...

, MFSD4A, MFSD4B, MFSD5, MFSD6, MFSD6L, MFSD8,

MFSD9 Major facilitator superfamily domain-containing protein 9 is a protein that in humans is encoded by the MFSD9 gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity. ...

, MFSD10,

MFSD11 Major facilitator superfamily The major facilitator superfamily (MFS) is a superfamily of membrane transport proteins that facilitate movement of small solutes across cell membranes in response to chemiosmotic gradients. Function The major fac ...

, MFSD12, MFSD13A, MFSD14A,

MFSD14B Major facilitator superfamily The major facilitator superfamily (MFS) is a superfamily of membrane transport proteins that facilitate movement of small solutes across cell membranes in response to chemiosmotic gradients. Function The major fac ...

UNC93A Unc-93 homolog A (C. elegans) is a protein that in humans is encoded by the UNC93A gene. Unc93A is a major facilitator superfamily (MFS), and a putative solute carrier in humans. It belongs to the atypical SLCs that was recently listed. It is th ...

and

UNC93B1 Unc-93 homolog B1 (''C. elegans''), also known as UNC93B1, is a protein which in humans is encoded by the ''UNC93B1'' gene. Function This gene encodes a protein with similarity to the ''Caenorhabditis elegans'' unc93 protein. The Unc93 protein ...

. All these are atypical SLCs found within the

Major facilitator superfamily The major facilitator superfamily (MFS) is a superfamily of membrane transport proteins that facilitate movement of small solutes across cell membranes in response to chemiosmotic gradients. Function The major facilitator superfamily (MFS) are ...

. Also TMEM104 (APC clan), OCA2 (IT clan) and CLN3 (having no clan) are atypical SLCs in humans.

Non-MFS transport families

Although most atypical SLCs are from the major facilitator superfamily, there are exceptions: TMEM104 ( APC superfamily), OCA2 (IT superfamily) and CLN3 (unknown superfamily).

References

Solute carrier family {{genetics-stub