Nomenclature of Toso, Fas apoptosis inhibitory molecule 3, and IgM FcR

J Immunol. 2015 May 1;194(9):4055-7. doi: 10.4049/jimmunol.1500222.


Hiromi Kubagawa and John E. Coligan coordinated an online meeting to define an appropriate nomenclature for the cell surface glycoprotein presently designated by different names: Toso, Fas apoptosis inhibitory molecule 3 (FAIM3), and IgM FcR (FcμR). FAIM3 and Faim3 are the currently approved symbols for the human and mouse genes, respectively, in the National Center for Biotechnology Information, Ensembl, and other databases. However, recent functional results reported by several groups of investigators strongly support a recommendation for renaming FAIM3/Faim3 as FCMR/Fcmr, a name better reflecting its physiological function as the FcR for IgM. Participants included 12 investigators involved in studying Toso/FAIM3(Faim3)/FμR, representatives from the Human Genome Nomenclature Committee (Ruth Seal) and the Mouse Genome Nomenclature Committee (Monica McAndrews), and an observer from the IgM research field (Michael Carroll). In this article, we provide a brief background of the key research on the Toso/FAIM3(Faim3)/FcμR proteins, focusing on the ligand specificity and functional activity, followed by a brief summary of discussion about adopting a single name for this molecule and its gene and a resulting recommendation for genome nomenclature committees.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis Regulatory Proteins* / genetics
  • Carrier Proteins* / genetics
  • Humans
  • Immunoglobulin M
  • Membrane Proteins* / genetics
  • Mice
  • Receptors, Fc / classification
  • Terminology as Topic*


  • Apoptosis Regulatory Proteins
  • Carrier Proteins
  • FCMR protein, human
  • Fcmr protein, mouse
  • Immunoglobulin M
  • Membrane Proteins
  • Receptors, Fc