TY - JOUR
T1 - PSD-95 and SAP97 exhibit distinct mechanisms for regulating K+ channel surface expression and clustering
AU - Tiffany, Amanda M.
AU - Manganas, Louis N.
AU - Kim, Eunjoon
AU - Hsueh, Yi Ping
AU - Sheng, Morgan
AU - Trimmer, James
PY - 2000/1/10
Y1 - 2000/1/10
N2 - Mechanisms of ion channel clustering by cytoplasmic membrane-associated guanylate kinases such as postsynaptic density 95 (PSD-95) and synapse- associated protein 97 (SAP97) are poorly understood. Here, we investigated the interaction of PSD-95 and SAP97 with voltage-gated or Kv K+ channels. Using Kv channels with different surface expression properties, we found that clustering by PSD-95 depended on channel cell surface expression. Moreover, PSD-95-induced clusters of Kv1 K+ channels were present on the cell surface. This was most dramatically demonstrated for Kv1.2 K+ channels, where surface expression and clustering by PSD-95 were coincidentally promoted by coexpression with cytoplasmic Kvβ subunits. Consistent with a mechanism of plasma membrane channel-PSD-95 binding, coexpression with PSD-95 did not affect the intrinsic surface expression characteristics of the different Kv channels. In contrast, the interaction of Kv1 channels with SAP97 was independent of Kv1 surface expression, occurred intracellularly, and prevented further biosynthetic trafficking of Kv1 channels. As such, SAP97 binding caused an intracellular accumulation of each Kv1 channel tested, through the accretion of SAP97 channel clusters in large (3-5 μm) ER-derived intracellular membrane vesicles. Together, these data show that ion channel clustering by PSD-95 and SAP97 occurs by distinct mechanisms, and suggests that these channel-clustering proteins may play diverse roles in regulating the abundance and distribution of channels at synapses and other neuronal membrane specializations.
AB - Mechanisms of ion channel clustering by cytoplasmic membrane-associated guanylate kinases such as postsynaptic density 95 (PSD-95) and synapse- associated protein 97 (SAP97) are poorly understood. Here, we investigated the interaction of PSD-95 and SAP97 with voltage-gated or Kv K+ channels. Using Kv channels with different surface expression properties, we found that clustering by PSD-95 depended on channel cell surface expression. Moreover, PSD-95-induced clusters of Kv1 K+ channels were present on the cell surface. This was most dramatically demonstrated for Kv1.2 K+ channels, where surface expression and clustering by PSD-95 were coincidentally promoted by coexpression with cytoplasmic Kvβ subunits. Consistent with a mechanism of plasma membrane channel-PSD-95 binding, coexpression with PSD-95 did not affect the intrinsic surface expression characteristics of the different Kv channels. In contrast, the interaction of Kv1 channels with SAP97 was independent of Kv1 surface expression, occurred intracellularly, and prevented further biosynthetic trafficking of Kv1 channels. As such, SAP97 binding caused an intracellular accumulation of each Kv1 channel tested, through the accretion of SAP97 channel clusters in large (3-5 μm) ER-derived intracellular membrane vesicles. Together, these data show that ion channel clustering by PSD-95 and SAP97 occurs by distinct mechanisms, and suggests that these channel-clustering proteins may play diverse roles in regulating the abundance and distribution of channels at synapses and other neuronal membrane specializations.
KW - COS cells
KW - Ion channel localization
KW - Membrane proteins
KW - Nerve tissue proteins
KW - Protein binding
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U2 - 10.1083/jcb.148.1.147
DO - 10.1083/jcb.148.1.147
M3 - Article
C2 - 10629225
AN - SCOPUS:0034627836
VL - 148
SP - 147
EP - 157
JO - Journal of Cell Biology
JF - Journal of Cell Biology
SN - 0021-9525
IS - 1
ER -