Transfection of the CD20 cell surface molecule into ectopic cell types generates a Ca2+ conductance found constitutively in B lymphocytes.

Published

Journal Article

CD20 is a plasma membrane phosphoprotein expressed exclusively by B lymphocytes. mAb binding to CD20 alters cell cycle progression and differentiation, indicating that CD20 plays an essential role in B lymphocyte function. Whole-cell patch clamp and fluorescence microscopy measurements of plasma membrane ionic conductance and cytosolic-free Ca2+ activity, respectively, were used to directly examine CD20 function. Transfection of human T and mouse pre-B lymphoblastoid cell lines with CD20 cDNA and subsequent stable expression of CD20 specifically increased transmembrane Ca2+ conductance. Transfection of CD20 cDNA and subsequent expression of CD20 in nonlymphoid cells (human K562 erythroleukemia cells and mouse NIH-3T3 fibroblasts) also induced the expression of an identical transmembrane Ca2+ conductance. The binding of a CD20-specific mAb to CD20+ lymphoblastoid cells also enhanced the transmembrane Ca2+ conductance. The mAb-enhanced Ca2+ currents had the same conductance characteristics as the CD20-associated Ca2+ currents in CD20 cDNA-transfected cells. C20 is structurally similar to several ion channels; each CD20 monomer possesses four membrane spanning domains, and both the amino and carboxy termini reside within the cytoplasm. Biochemical cross-linking of cell-surface molecules with subsequent immunoprecipitation analysis of CD20 suggests that CD20 may be present as a multimeric oligomer within the membrane, as occurs with several known membrane channels. Taken together, these findings indicate that CD20 directly regulates transmembrane Ca2+ conductance in B lymphocytes, and suggest that multimeric complexes of CD20 may form Ca2+ conductive ion channels in the plasma membrane of B lymphoid cells.

Full Text

Duke Authors

Cited Authors

  • Bubien, JK; Zhou, LJ; Bell, PD; Frizzell, RA; Tedder, TF

Published Date

  • June 1, 1993

Published In

Volume / Issue

  • 121 / 5

Start / End Page

  • 1121 - 1132

PubMed ID

  • 7684739

Pubmed Central ID

  • 7684739

Electronic International Standard Serial Number (EISSN)

  • 1540-8140

International Standard Serial Number (ISSN)

  • 0021-9525

Digital Object Identifier (DOI)

  • 10.1083/jcb.121.5.1121

Language

  • eng