Activation-induced endocytosis of the raft-associated transmembrane adaptor protein LAB/NTAL in B lymphocytes: evidence for a role in internalization of the B cell receptor.

Journal Article

Linker for activation of B cell (LAB)/non-T cell activation linker (NTAL) and phosphoprotein associated with glycophospholipid-enriched membrane microdomain (PAG)/Csk-binding protein (Cbp) are raft-associated transmembrane adaptor proteins with distinct functions in immediate/early phases of receptor signaling pathways. Heterogeneous rafts are thought to compartmentalize membrane-associated signaling events. In order to investigate the subcellular localization of LAB/NTAL and PAG/Cbp, they were expressed as fluorescent chimeric fusion proteins in a human B cell line and their distribution was examined, along with the corresponding endogenous proteins, before and after B cell receptor (BCR) stimulation. Both adaptors were distributed predominantly at the plasma membrane in resting cells and co-clustered with other raft-associated proteins; however, they distributed differently in buoyant membranes isolated by either detergent resistance or non-detergent methods, indicating that they might localize to distinct rafts. After activation, LAB/NTAL was internalized and co-localized with the BCR while PAG/Cbp remained on the cell surface. BCR internalization was reduced in LAB/NTAL-deficient murine B cells, suggesting a regulatory role for LAB/NTAL in activation-induced internalization of the BCR. The cytoplasmic domain of LAB/NTAL, and not the transmembrane/juxtamembrane region, was found to be essential for its internalization.

Full Text

Duke Authors

Cited Authors

  • Mutch, CM; Sanyal, R; Unruh, TL; Grigoriou, L; Zhu, M; Zhang, W; Deans, JP

Published Date

  • January 1, 2007

Published In

Volume / Issue

  • 19 / 1

Start / End Page

  • 19 - 30

PubMed ID

  • 17090619

Pubmed Central ID

  • 17090619

International Standard Serial Number (ISSN)

  • 0953-8178

Digital Object Identifier (DOI)

  • 10.1093/intimm/dxl118


  • eng

Conference Location

  • England