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 within the major facilitator superfamily (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,

CLN3 G1/S-specific cyclin Cln3 is a protein that is encoded by the ''CLN3'' gene. The Cln3 protein is a Saccharomyces cerevisiae, budding yeast G1 and G1/S cyclins- budding yeast, G1 cyclin that controls the timing of Start point (yeast), ''Start'', ...

, SPNS1,

SPNS2 Spinster homolog 2 (Drosophila) is a protein that in humans is encoded by the ''SPNS2'' gene. Model organisms Model organisms have been used in the study of SPNS2 function. A conditional knockout mouse line, called ''Spns2tm1a(KOMP)Wtsi ...

, SPNS3,

SV2A Synaptic vesicle glycoprotein 2A is a ubiquitous synaptic vesicle protein that in humans is encoded by the ''SV2A'' gene. The protein is targeted by the anti-epileptic drugs (anticonvulsants) levetiracetam and brivaracetam Brivaracetam, sold u ...

SV2B Synaptic vesicle glycoprotein 2B is a protein that in humans is encoded by the ''SV2B'' gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation ...

, SV2C, SVOP, SVOPL,

MFSD1 Major facilitator superfamily domain containing 1 (MFSD1, SMAP) is a protein belonging to the MFS Pfam clan. It is an Atypical solute carrier. It belongs to the major facilitator superfamily MFS Pfam Pfam is a database of protein families t ...

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, MFSD4A, MFSD4B, MFSD5, MFSD6, MFSD6L,

MFSD8 Major facilitator superfamily domain containing 8 also called MFSD8 is a protein that in humans is encoded by the ''MFSD8'' gene. MFSD8 is an atypical SLC, thus a predicted SLC transporter. It clusters phylogenetically to the Atypical MFS Trans ...

, MFSD9, MFSD10, MFSD11, MFSD12, MFSD13A, MFSD14A, MFSD14B, UNC93A and UNC93B1. All these are atypical SLCs found within the Major facilitator superfamily. 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