Encyclopedia of Biophysics

Living Edition
| Editors: Gordon Roberts, Anthony Watts, European Biophysical Societies

Membrane Transport Proteins: The Amino Acid-Polyamine-Organocation (APC) Superfamily

  • Alexander D. Cameron
  • Scott M. Jackson
  • Antonio N. Calabrese
  • Oliver Beckstein
  • Peter J. F. HendersonEmail author
Living reference work entry
DOI: https://doi.org/10.1007/978-3-642-35943-9_772-1


The proteins listed below belong to the amino acid-polyamine-organocation (APC) superfamily as defined by Wong et al. (2012) and Vastermark and Saier (2014). Structurally, this superfamily can be divided into two groups: the LeuT superfamily (Krishnamurthy et al. 2009), also known as the five-helix inverted repeat (5HIR) transporter superfamily (Adelman et al. 2011), and transporters with a seven-helix inverted repeat. These latter transporters are more distantly related.


The general transport reactions of this superfamily (Fig. 1) can be represented as follows:
  • Substrate (out) + nH+ (out) → Substrate (in) + nH+ (in)

  • Substrate (out) + nNa+ (out) → Substrate (in) + nNa+ (in)

  • Substrate-1 (out) + Substrate-2 (in) → Substrate-1 (in) + Substrate-2 (out)

  • Substrate-(out) ↔ Substrate-(in)

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Copyright information

© European Biophysical Societies' Association (EBSA) 2019

Authors and Affiliations

  • Alexander D. Cameron
    • 1
  • Scott M. Jackson
    • 2
  • Antonio N. Calabrese
    • 3
  • Oliver Beckstein
    • 4
  • Peter J. F. Henderson
    • 3
    Email author
  1. 1.School of Life SciencesUniversity of WarwickCoventryUK
  2. 2.Institute of Molecular Biology and Biophysics ETH ZurichZurichSwitzerland
  3. 3.Astbury Centre for Structural Molecular Biology and School of BioMedical SciencesUniversity of LeedsLeedsUK
  4. 4.Center for Biological Physics and Department of PhysicsArizona State UniversityTempeUSA

Section editors and affiliations

  • Peter J. F. Henderson
    • 1
  1. 1.Astbury Centre for Structural Molecular Biology and School of BioMedical SciencesUniversity of LeedsLeedsUK