Figures & data
Figure 1. N- and C-terminal assembly domains found in the superfamily of voltage-gated cation channels. (a) Schematic representation of a Kv pore-forming subunit. The N-terminal location of the T1 domain is indicated and the corresponding crystal structure obtained for four assembled T1 domains of Kv1.2 Citation[109] is shown. (b) Schematic representation of the KCNQ7 pore-forming subunit. The location of the C-terminal A-domain tail, a self-assembling, parallel, four-stranded coiled-coil, is shown along with the corresponding crystal structure of four assembled coiled-coil forming domains Citation[39]. Structure reproduced from Citation[109] and Citation[39] with permission from Elsevier.
![Figure 1. N- and C-terminal assembly domains found in the superfamily of voltage-gated cation channels. (a) Schematic representation of a Kv pore-forming subunit. The N-terminal location of the T1 domain is indicated and the corresponding crystal structure obtained for four assembled T1 domains of Kv1.2 Citation[109] is shown. (b) Schematic representation of the KCNQ7 pore-forming subunit. The location of the C-terminal A-domain tail, a self-assembling, parallel, four-stranded coiled-coil, is shown along with the corresponding crystal structure of four assembled coiled-coil forming domains Citation[39]. Structure reproduced from Citation[109] and Citation[39] with permission from Elsevier.](/cms/asset/48715a9b-3947-47cc-9fa7-9bc90ca4a9e5/imbc_a_296265_f0001_b.jpg)
Figure 2. Major mechanisms involved in general and protein-specific quality control. Following the terminology introduced by Ellgaard and Helenius Citation[3] primary (a; closed triangles) and secondary (b; open triangles) quality control processes are shown. The assembling subunits of a heteromultimeric channel are shown as rectangular shapes. Large dashed arrows indicate forward transport and ER retrieval. (a) General chaperones assist the folding of channels with luminal domains and monitor core glycosylation Citation[3]. Assembly intermediates exposing polar residues in the plane of the membrane can be eliminated by ERAD Citation[2]. Alternatively, they can be prevented from leaving the ER-Golgi shuttle by the retrieval factor Rer1 Citation[45], Citation[46]. (b) Herrmann et al. divided protein-specific chaperones into outfitters, escorts and guides Citation[81]. Many auxiliary subunits of ion channels can perform these functions for the specific pore-forming subunit(s) that they interact with. Beyond quality control, they usually contribute to the functional properties of the channel at the cell surface. Adapted with permission from Citation[5].
![Figure 2. Major mechanisms involved in general and protein-specific quality control. Following the terminology introduced by Ellgaard and Helenius Citation[3] primary (a; closed triangles) and secondary (b; open triangles) quality control processes are shown. The assembling subunits of a heteromultimeric channel are shown as rectangular shapes. Large dashed arrows indicate forward transport and ER retrieval. (a) General chaperones assist the folding of channels with luminal domains and monitor core glycosylation Citation[3]. Assembly intermediates exposing polar residues in the plane of the membrane can be eliminated by ERAD Citation[2]. Alternatively, they can be prevented from leaving the ER-Golgi shuttle by the retrieval factor Rer1 Citation[45], Citation[46]. (b) Herrmann et al. divided protein-specific chaperones into outfitters, escorts and guides Citation[81]. Many auxiliary subunits of ion channels can perform these functions for the specific pore-forming subunit(s) that they interact with. Beyond quality control, they usually contribute to the functional properties of the channel at the cell surface. Adapted with permission from Citation[5].](/cms/asset/c914268a-5b4e-48a9-8a91-e28777cefa25/imbc_a_296265_f0002_b.gif)