Loss of the beta 1 subunit of the sodium pump during lymphocyte differentiation.
The Na,K-ATPase, or sodium pump, is responsible for maintaining cellular volume and is involved in receptor-mediated endocytosis; it is a ubiquitous transmembrane enzyme in higher eukaryotes and consists of an alpha and a beta subunit. In the mouse, two isotypes of beta with no known function have been identified: beta 1 and beta 2. We have studied the expression of beta 1 and beta 2 in lymphocytes from bone marrow, spleen, peripheral blood, and thymus. The beta 2 subunit is not expressed in any of the lymphocytes tested. Pre-B lymphocytes and the majority of mature, resting B cells in the bone marrow express the beta 1 subunit, as do all pre-T cells and mature thymocytes. In the spleen and in blood, beta 1 expression defines subsets of T and B lymphocytes. Mitogen-stimulated T and B cells lose beta 1 expression and do not express beta 2. While there is no indication that there is a change in alpha subunit isoform expression as a result of lymphocyte activation or that it is expressed in smaller amounts, there is a switch in the expression of the beta isoform.
Masat
L
L
Department of Microbiology and Immunology, University of California, San Francisco 94143-0670, USA.
Cascalho
M
M
Wabl
M
M
D000818:Animals; D001402:B-Lymphocytes / Q000201:enzymology* / Q000276:immunology; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D000254:Sodium-Potassium-Exchanging ATPase / Q000172:deficiency* / Q000276:immunology*; D013601:T-Lymphocytes / Q000201:enzymology* / Q000276:immunology
D000254:Sodium-Potassium-Exchanging ATPase