Structure and function of the beta 2 subunit of brain sodium channels, a transmembrane glycoprotein with a CAM motif

Cell. 1995 Nov 3;83(3):433-42. doi: 10.1016/0092-8674(95)90121-3.


Voltage-gated sodium channels in brain neurons are complexes of a pore-forming alpha subunit with smaller beta 1 and beta 2 subunits. cDNA cloning and sequencing showed that the beta 2 subunit is a 186 residue glycoprotein with an extracellular NH2-terminal domain containing an immunoglobulin-like fold with similarity to the neural cell adhesion molecule (CAM) contactin, a single transmembrane segment, and a small intracellular domain. Coexpression of beta 2 with alpha subunits in Xenopus oocytes increases functional expression, modulates gating, and causes up to a 4-fold increase in the capacitance of the oocyte, which results from an increase in the surface area of the plasma membrane microvilli. beta 2 subunits are unique among the auxiliary subunits of ion channels in combining channel modulation with a CAM motif and the ability to expand the cell membrane surface area. They may be important regulators of sodium channel expression and localization in neurons.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Brain / embryology
  • Brain Chemistry / physiology*
  • Cell Adhesion Molecules / physiology*
  • Cell Adhesion Molecules, Neuronal*
  • Cell Membrane / physiology
  • Cloning, Molecular
  • Contactins
  • DNA, Complementary / genetics
  • Gene Expression / physiology
  • Immunoglobulins / genetics
  • Membrane Glycoproteins / physiology
  • Molecular Sequence Data
  • Nerve Tissue Proteins / genetics
  • Oocytes / physiology
  • Rats
  • Sodium Channels / physiology*
  • Sodium Channels / ultrastructure
  • Spinal Cord / chemistry
  • Spinal Cord / embryology
  • Xenopus


  • Cell Adhesion Molecules
  • Cell Adhesion Molecules, Neuronal
  • Contactins
  • DNA, Complementary
  • Immunoglobulins
  • Membrane Glycoproteins
  • Nerve Tissue Proteins
  • Sodium Channels

Associated data

  • GENBANK/U37026
  • GENBANK/U37147