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The beta1 subunit of the large conductance, Ca 2+ ‐activated K + channel (BK‐β1) is localized on the apical membrane of non‐IC cells within the mouse connecting tubule (CNT)
Author(s) -
Grimm Paul R.,
Pluznick Jennifer L.,
Foutz Ruth M.,
Wei Peilin,
Sansom Steven S.
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a1227-c
Subject(s) - protein subunit , secretion , chemistry , apical membrane , biophysics , intercalated cell , antibody , microbiology and biotechnology , biology , biochemistry , membrane , immunology , gene
Nebraska Medical Center, Omaha, Nebraska, 68198‐5850 It is increasingly evident that the BK channel, which is comprised of pore‐forming α subunits and one of four accessory β subunits, is responsible for flow‐dependent K + secretion in mammals. However, the α‐subunit is expressed in many segments of the nephron not involved in flow‐mediated K + secretion. Therefore, it is probable that the response of BK to flow is largely dependent on the association of the α‐subunit with a specific β subunit that confers flow‐sensitive properties to BK. We recently showed with BK‐β1−/− mice that flow‐mediated K + secretion is dependent on the presence of the β1 subunit, which is localized to the apical membrane of the CNT. Although the CNT is comprised of a heterogeneous mixture of three cell types, many studies have concluded that principal cells (PC) of the distal nephron (including the connecting‐tubule cells of the CNT) are ideally suited to respond to mediators of K + secretion. In immunohistochemical experiments, we found that peanut lectin (an intercalated cell (IC) marker) and a β1‐subunit antibody labeled separate cells in the same tubule. To confirm these results, we used a β1 subunit antibody along with an antibody for the vacuolar hydrogen ATPase (V‐ATPase), which labels intercalated cells. Once again, we found that the β1 subunit and V‐ATPase antibodies labeled separate cells. We conclude that the β1 subunit is located exclusively within the apical membrane of the connecting‐tubule cells of the CNT. Supported by RO1‐DK49561 and 1T32HL0788.