Disinactivation of N-type inactivation of voltage-gated K channels by an erbstatin analogue.
In some A-type voltage-gated K channels, rapid inactivation is achieved through the binding of an N-terminal domain of the pore-forming alpha-subunit or an associated beta-subunit to a cytoplasmic acceptor located at or near the channel pore using the ball-and-chain machinery (1-5). This inactivation involving the N terminus is known as N-type inactivation. Here, we describe an erbstatin (Erb) analogue as a small molecule inhibitor of the N-type inactivation in channels of Kv1.4 and Kv1.1+Kvbeta1. We show that this inhibition of inactivation (designated as "disinactivation") is potent and selective for N-type inactivation in heterologous cells (Chinese hamster ovary and Xenopus oocytes) expressing these A-type channels. In Chinese hamster ovary cells, Erb increased the inactivation time constant of Kv1.4 from 86.5 +/- 9.5 to 150 +/- 10 ms (n = 6, p < 0.0 1). Similarly, Erb increased the inactivation time constant of Kv1.1+Kvbeta1 from 10 +/- 0.9 to 49.3 +/- 7 ms (n = 7, p < 0.01). The EC(50) for disinactivating Kv1.1+Kvbeta1 was 10.4 +/- 0.9 microm (n = 2-9). Erb had no effect upon another A-channel, Kv4.3, which does not utilize the ball-and-chain mechanism. The mechanism of Erb-induced disinactivation was also investigated. Neither cysteine oxidation nor tyrosine kinase inhibition was involved. The results demonstrate that Erb can be used as a base structure to identify potent, selective small molecule inhibitors of intracellular protein-protein interactions, and that these disinactivators may offer another therapeutic approach to the treatment of seizure disorders.
Zhang
Zhi-Hao
ZH
Department of Women's Health and Bone, Wyeth Research, Collegeville, Pennsylvania 19426, USA.
Rhodes
Kenneth J
KJ
Childers
Wayne E
WE
Argentieri
Thomas M
TM
Wang
Qiang
Q
D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D006873:Hydroquinones / Q000737:chemistry* / Q000378:metabolism*; D051662:Kv1.1 Potassium Channel; D051665:Kv1.4 Potassium Channel; D008564:Membrane Potentials / Q000502:physiology; D008958:Models, Molecular; D015394:Molecular Structure; D009865:Oocytes / Q000502:physiology; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated; D017433:Protein Structure, Secondary; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011725:Pyridines / Q000378:metabolism; D014981:Xenopus
D004791:Enzyme Inhibitors; D006873:Hydroquinones; C496946:KCNA1 protein, human; C496977:KCNA4 protein, human; D051665:Kv1.4 Potassium Channel; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D011725:Pyridines; D051662:Kv1.1 Potassium Channel; C011801:2,2'-dithiobis(5-nitropyridine); D011505:Protein-Tyrosine Kinases; C048212:erbstatin