TY - JOUR
T1 - Properties of gap junction channels formed by Cx46 alone and in combination with Cx50
AU - Hopperstad, Matthew G.
AU - Srinivas, Miduturu
AU - Spray, David C.
N1 - Funding Information:
This work was supported in part by an AHA Heritage Postdoctoral Fellowship to MS and by a National Institutes of Health grant (EY08969) to DCS.
PY - 2000
Y1 - 2000
N2 - Gap junctions formed of connexin46 (Cx46) and connexin50 (Cx50) in lens fiber cells are crucial for maintaining lens transparency. We determined the functional properties of homotypic Cx46, heterotypic Cx46/Cx50, and heteromeric Cx46/Cx50 channels in a communication-deficient neuroblastoma (N2A) cell line, using dual whole-cell recordings. N2A cultures were stably and/or transiently transfected with Cx46, Cx50, and green fluorescent protein (EGFP). The macroscopic voltage sensitivity of homotypic Cx46 conformed to the two-state model (Boltzmann parameters: G(min) = 0.11, V(o) = ± 48.1 mV, gating charge = 2). Cx46 single channels showed a main-state conductance of 140 ± 8 pS and multiple subconductance states ranging from ≤ 10 pS to 60 pS. Conservation of homotypic properties in heterotypic Cx46/Cx50 cell pairs allowed the determination of a positive relative gating polarity for the dominant gating mechanisms in Cx46 and Cx50. Observed gating properties were consistent with a second gating mechanism in Cx46 connexons. Moreover, rectification was observed in heterotypic cell pairs. Some cell pairs in cultures simultaneously transfected with Cx46 and Cx50 exhibited junctional properties not observed in other preparations, suggesting the formation of heteromeric channels. We conclude that different combinations of Cx46 and Cx50 within gap junction channels lead to unique biophysical properties.
AB - Gap junctions formed of connexin46 (Cx46) and connexin50 (Cx50) in lens fiber cells are crucial for maintaining lens transparency. We determined the functional properties of homotypic Cx46, heterotypic Cx46/Cx50, and heteromeric Cx46/Cx50 channels in a communication-deficient neuroblastoma (N2A) cell line, using dual whole-cell recordings. N2A cultures were stably and/or transiently transfected with Cx46, Cx50, and green fluorescent protein (EGFP). The macroscopic voltage sensitivity of homotypic Cx46 conformed to the two-state model (Boltzmann parameters: G(min) = 0.11, V(o) = ± 48.1 mV, gating charge = 2). Cx46 single channels showed a main-state conductance of 140 ± 8 pS and multiple subconductance states ranging from ≤ 10 pS to 60 pS. Conservation of homotypic properties in heterotypic Cx46/Cx50 cell pairs allowed the determination of a positive relative gating polarity for the dominant gating mechanisms in Cx46 and Cx50. Observed gating properties were consistent with a second gating mechanism in Cx46 connexons. Moreover, rectification was observed in heterotypic cell pairs. Some cell pairs in cultures simultaneously transfected with Cx46 and Cx50 exhibited junctional properties not observed in other preparations, suggesting the formation of heteromeric channels. We conclude that different combinations of Cx46 and Cx50 within gap junction channels lead to unique biophysical properties.
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U2 - 10.1016/S0006-3495(00)76444-7
DO - 10.1016/S0006-3495(00)76444-7
M3 - Article
C2 - 11023900
AN - SCOPUS:0033808250
SN - 0006-3495
VL - 79
SP - 1954
EP - 1966
JO - Biophysical journal
JF - Biophysical journal
IS - 4
ER -