TY - JOUR
T1 - Independent trafficking of K(ATP) channel subunits to the plasma membrane
AU - Makhina, Elena N.
AU - Nichols, Colin G.
PY - 1998/2/6
Y1 - 1998/2/6
N2 - K(ATP) channels are unique in requiring two distinct subunits (Kir6.2, a potassium channel subunit) and SUR1 (an ABC protein) for generation of functional channels. To examine the cellular trafficking of K(ATP) channel subunits, green fluorescent protein (GFP) was tagged to the cytoplasmic N or C terminus of SUR1 and Kir6.2 subunits and to the C terminus of a dimeric fusion between SUR1 and Kir6.2 (SUR1-Kir6.2). All tagged constructs generated functional channels with essentially normal properties when coexpressed with the relevant other subunit. GFP-tagged Kir6.2 (Kir6.2-GFP) showed perinuclear and plasma membrane fluorescence patterns when expressed alone or with SUR1, and a very similar pattern was observed when channel-forming SUR1-Kir6.2-GFP was expressed on its own. In contrast, whereas SUR1 (SUR1-GFP) also showed a perinuclear and plasma membrane fluorescence pattern when expressed alone, an apparently cytoplasmic fluorescence was observed when coexpressed with Kir6.2 subunits. The results indicate that Kir6.2 subunits traffic to the plasma membrane in the presence or absence of SUR1, in contradiction to the hypothesis that homomeric Kir6.2 channels are not observed because SUR1 is required as a chaperone to guide Kir6.2 subunits through the secretory pathway.
AB - K(ATP) channels are unique in requiring two distinct subunits (Kir6.2, a potassium channel subunit) and SUR1 (an ABC protein) for generation of functional channels. To examine the cellular trafficking of K(ATP) channel subunits, green fluorescent protein (GFP) was tagged to the cytoplasmic N or C terminus of SUR1 and Kir6.2 subunits and to the C terminus of a dimeric fusion between SUR1 and Kir6.2 (SUR1-Kir6.2). All tagged constructs generated functional channels with essentially normal properties when coexpressed with the relevant other subunit. GFP-tagged Kir6.2 (Kir6.2-GFP) showed perinuclear and plasma membrane fluorescence patterns when expressed alone or with SUR1, and a very similar pattern was observed when channel-forming SUR1-Kir6.2-GFP was expressed on its own. In contrast, whereas SUR1 (SUR1-GFP) also showed a perinuclear and plasma membrane fluorescence pattern when expressed alone, an apparently cytoplasmic fluorescence was observed when coexpressed with Kir6.2 subunits. The results indicate that Kir6.2 subunits traffic to the plasma membrane in the presence or absence of SUR1, in contradiction to the hypothesis that homomeric Kir6.2 channels are not observed because SUR1 is required as a chaperone to guide Kir6.2 subunits through the secretory pathway.
UR - http://www.scopus.com/inward/record.url?scp=0032488663&partnerID=8YFLogxK
U2 - 10.1074/jbc.273.6.3369
DO - 10.1074/jbc.273.6.3369
M3 - Article
C2 - 9452456
AN - SCOPUS:0032488663
VL - 273
SP - 3369
EP - 3374
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 6
ER -