The B cell-specific major raft protein, Raftlin, is necessary for the integrity of lipid raft and BCR signal transduction

EMBO J. 2003 Jun 16;22(12):3015-26. doi: 10.1093/emboj/cdg293.


Recent evidence indicates that membrane microdomains, termed lipid rafts, have a role in B-cell activation as platforms for B-cell antigen receptor (BCR) signal initiation. To gain an insight into the possible functioning of lipid rafts in B cells, we applied liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) methodologies to the identification of proteins that co-purified with lipid rafts of Raji cells. Among these raft proteins, we characterized a novel protein termed Raftlin (raft-linking protein). Like the Src family kinase, Raftlin is localized exclusively in lipid rafts by fatty acylation of N-terminal Gly2 and Cys3, and is co-localized with BCR before and after BCR stimulation. Disruption of the Raftlin gene in the DT40 B-cell line resulted in a marked reduction in the quantity of lipid raft components, including Lyn and ganglioside GM1, while overexpression of Raftlin increased the content of raft protein. Moreover, BCR-mediated tyrosine phosphorylation and calcium mobilization were impaired by the lack of Raftlin and actually potentiated by overexpression of Raftlin. These data suggest that Raftlin plays a pivotal role in the formation and/or maintenance of lipid rafts, therefore regulating BCR-mediated signaling.

Publication types

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

MeSH terms

  • Acylation
  • Amino Acid Sequence
  • Animals
  • B-Lymphocytes / metabolism*
  • Cell Fractionation
  • Cell Line
  • Chickens
  • Humans
  • Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / genetics
  • Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / metabolism
  • Membrane Microdomains / chemistry*
  • Membrane Microdomains / metabolism*
  • Membrane Proteins / chemistry
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Molecular Sequence Data
  • Receptors, Antigen, B-Cell / metabolism*
  • Recombinant Fusion Proteins / metabolism
  • Sequence Alignment
  • Signal Transduction / physiology*
  • Spectrometry, Mass, Electrospray Ionization
  • Tissue Distribution


  • Membrane Proteins
  • RFTN1 protein, human
  • Receptors, Antigen, B-Cell
  • Recombinant Fusion Proteins
  • Lymphocyte Specific Protein Tyrosine Kinase p56(lck)

Associated data

  • GENBANK/AB092511