TY - JOUR
T1 - FRET two-hybrid mapping reveals function and location of L-type Ca2+ channel CaM preassociation
AU - Erickson, Michael G.
AU - Liang, Haoya
AU - Mori, Masayuki X.
AU - Yue, David T.
N1 - Funding Information:
We thank Jenafer Evans for discussion. This work was supported by a Whitaker Foundation Graduate Fellowship (M.G.E.) and grants from the American Heart Association and National Institutes of Health (D.T.Y.).
PY - 2003/7/3
Y1 - 2003/7/3
N2 - L-type Ca2+ channels possess a Ca2+-dependent inactivation (CDI) mechanism, affording feedback in diverse neurobiological settings and serving as prototype for unconventional calmodulin (CaM) regulation emerging in many Ca2+ channels. Crucial to such regulation is the preassociation of Ca2+-free CaM (apoCaM) to channels, facilitating rapid triggering of CDI as Ca2+/CaM shifts to a channel IQ site (IQ). Progress has been hindered by controversy over the preassociation site, as identified by in vitro assays. Most critical has been the failure to resolve a functional signature of preassociation. Here, we deploy novel FRET assays in live cells to identify a 73 aa channel segment, containing IQ, as the critical preassociation pocket. IQ mutations disrupting preassociation revealed accelerated voltage-dependent inactivation (VDI) as the functional hallmark of channels lacking preassociated CaM. Hence, the α1C IQ segment is multifunctional - serving as ligand for preassociation and as Ca2+/CaM effector site for CDI.
AB - L-type Ca2+ channels possess a Ca2+-dependent inactivation (CDI) mechanism, affording feedback in diverse neurobiological settings and serving as prototype for unconventional calmodulin (CaM) regulation emerging in many Ca2+ channels. Crucial to such regulation is the preassociation of Ca2+-free CaM (apoCaM) to channels, facilitating rapid triggering of CDI as Ca2+/CaM shifts to a channel IQ site (IQ). Progress has been hindered by controversy over the preassociation site, as identified by in vitro assays. Most critical has been the failure to resolve a functional signature of preassociation. Here, we deploy novel FRET assays in live cells to identify a 73 aa channel segment, containing IQ, as the critical preassociation pocket. IQ mutations disrupting preassociation revealed accelerated voltage-dependent inactivation (VDI) as the functional hallmark of channels lacking preassociated CaM. Hence, the α1C IQ segment is multifunctional - serving as ligand for preassociation and as Ca2+/CaM effector site for CDI.
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U2 - 10.1016/S0896-6273(03)00395-7
DO - 10.1016/S0896-6273(03)00395-7
M3 - Article
C2 - 12848935
AN - SCOPUS:0037629688
SN - 0896-6273
VL - 39
SP - 97
EP - 107
JO - Neuron
JF - Neuron
IS - 1
ER -