The effects of Shaker beta-subunits on the human lymphocyte K+ channel Kv1.3.
The activation of T-lymphocytes is dependent upon, and accompanied by, an increase in voltage-gated K+ conductance. Kv1.3, a Shaker family K+ channel protein, appears to play an essential role in the activation of peripheral human T cells. Although Kv1.3-mediated K+ currents increase markedly during the activation process in mice, and to a lesser degree in humans, Kv1.3 mRNA levels in these organisms do not, indicating post-transcriptional regulation. In other tissues Shaker K+ channel proteins physically associate with cytoplasmic beta-subunits (Kvbeta1-3). Recently it has been shown that Kvbeta1 and Kvbeta2 are expressed in mouse T cells and that they are up-regulated during mitogen-stimulated activation. In this study, we show that the human Kvbeta subunits substantially increase K+ current amplitudes when coexpressed with their Kv1.3 counterpart, and that unlike in mouse, protein levels of human Kvbeta2 remain constant upon activation. Differences in Kvbeta2 expression between mice and humans may explain the differential K+ conductance increases which accompany T-cell proliferation in these organisms.
Department of Physiology and Neuroscience, New York University, School of Medicine, New York, New York 10016, USA.
T
T
McCormack
K
K
McCormack
M S
MS
Nadal
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E
Vieira
A
A
Ozaita
B
B
Rudy
D000818:Animals; D002478:Cells, Cultured; D005260:Female; D006801:Humans; D051664:Kv1.3 Potassium Channel; D051379:Mice; D010455:Peptides / Q000737:chemistry*; D015221:Potassium Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated; D018075:RNA, Complementary / Q000235:genetics / Q000378:metabolism; D051637:Shaker Superfamily of Potassium Channels; D014982:Xenopus laevis
C496973:KCNA3 protein, human; C496974:Kcna3 protein, mouse; D051664:Kv1.3 Potassium Channel; D010455:Peptides; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D018075:RNA, Complementary; C076413:Shaker B potassium channel polypeptide; D051637:Shaker Superfamily of Potassium Channels