title: TOG superfamily
text: # TOG superfamily
  
  The transporter-opsin-G protein-coupled receptor (TOG) superfamily is a protein superfamily of integral membrane proteins, usually of 7 or 8 transmembrane alpha-helical segments (TMSs). It includes (1) ion-translocating microbial rhodopsins and (2) G protein-coupled receptors (GPCRs), (3) Sweet sugar transporters, (4) nicotinamide ribonucleoside uptake permeases (PnuC; TC# 4.B.1), (5) 4-toluene sulfonate uptake permeases (TSUP); TC# 2.A.102), (6) $Ni^{2+}–Co^{2+}$ transporters (NiCoT); TC# 2.A.52), (7) organic solute transporters (OST); TC# 2.A.82), (8) $phosphate:Na^+$ symporters (PNaS); TC# 2.A.58) and (9) lysosomal cystine transporters (LCT); TC# 2.A.43).
  
  ## Families
  
  Currently recognized families within the TOG Superfamily (with TC numbers in blue) include:
  
  * 1.A.14 - The Testis-enhanced Gene Transfer (TEGT) Family
  * 1.A.26 - The $Mg^{2+}$ Transporter-E (MgtE) Family
  * 1.A.76 - The Magnesium Transporter1 (MagT1) Family
  * 2.A.43 - The Lysosomal Cystine Transporter (LCT) Family
  * 2.A.52 - The $Ni^{2+}-Co^{2+}$ Transporter (NiCoT) Family
  * 2.A.58 - The $Phosphate:Na^+$ Symporter (PNaS) Family
  * 2.A.82 - The Organic Solute Transporter (OST) Family
  * 2.A.102 - The 4-Toluene Sulfonate Uptake Permease (TSUP) Family
  * 2.A.123 - The Sweet; PQ-loop; Saliva; MtN3 (Sweet) Family
  * 3.E.1 - The Ion-translocating Microbial Rhodopsin (MR) Family
  * 4.B.1 - The Nicotinamide Ribonucleoside (NR) Uptake Permease (PnuC) Family
  * 9.A.14 - The G-protein-coupled receptor (GPCR) Family
  
  ## Structures
  
  A couple of the 3-D structures available for members of the following families include:
  
  * SWEET family: 4RNG​
  * MR family: 5AX0​, 3T45​ - high resolution structures
  * PnuC family: 4QTN​
  * GPCR family: 3CAP​
  