Opposite effects of a single IIIS5 mutation on phenylalkylamine and dihydropyridine interaction with L-type Ca2+ channels

Replacement of L-type Ca(2+) channel alpha(1) subunit residue Thr-1066 in segment IIIS5 by a tyrosine residue conserved in the corresponding positions of non-L-type Ca(2+) channels eliminates high dihydropyridine sensitivity through a steric mechanism. To determine the effects of this mutation on phenylalkylamine interaction, we exploited the availability of Ca(v)1.2DHP(-/-) mice containing the T1066Y mutation. In contrast to dihydropyridines, increased protein-dependent binding of the phenylalkylamine (-)-[(3)H]devapamil occurred to Ca(v)1.2DHP(-/-) mouse brain microsomes. This effect could be attributed to an at least 2-fold increase in affinity as determined by saturation analysis and binding inhibition experiments. The latter also revealed a higher affinity for (-)-verapamil but not for (-)-gallopamil. The mutation caused a pronounced slowing of (-)-[(3)H]devapamil dissociation, indicating a stabilization of the drug-channel complex. The increased affinity of mutant channels was also evident in functional studies after heterologous expression of wild type and T1066Y channels in Xenopus laevis oocytes. 100 mum (-)-verapamil inhibited a significantly larger fraction of Ba(2+) inward current through mutant than through WT channels. Our results provide evidence that phenylalkylamines also interact with the IIIS5 helix and that the geometry of the IIIS5 helix affects the access and/or binding of different chemical classes of Ca(2+) channel blockers to their overlapping binding domains. Mutation of Thr-1066 to a non-L-type tyrosine residue can be exploited to differentially affect phenylalkylamine and dihydropyridine binding to L-type Ca(2+) channels.

Medienart:

Artikel

Erscheinungsjahr:

2004

Erschienen:

2004

Enthalten in:

Zur Gesamtaufnahme - volume:279

Enthalten in:

The Journal of biological chemistry - 279(2004), 53 vom: 31. Dez., Seite 55211-7

Sprache:

Englisch

Beteiligte Personen:

Huber, Irene G [VerfasserIn]
Wappl-Kornherr, Edwin [VerfasserIn]
Sinnegger-Brauns, Martina J [VerfasserIn]
Hoda, Jean-Charles [VerfasserIn]
Walter-Bastl, Doris [VerfasserIn]
Striessnig, Jörg [VerfasserIn]

Themen:

1,4-dihydropyridine
39WPC8JHR8
42HK56048U
7M8K3P6I89
CJ0O37KU29
Calcium
Calcium Channels
Calcium Channels, L-Type
Carrier Proteins
DNA, Complementary
Devapamil
Dihydropyridines
EC 5.3.3.-
Ebp protein, mouse
Gallopamil
Isradipine
Journal Article
L-type calcium channel alpha(1C)
M6142PTV7J
RNA, Complementary
Recombinant Proteins
Research Support, Non-U.S. Gov't
SY7Q814VUP
Steroid Isomerases
Tyrosine
Verapamil
YO1UK1S598

Anmerkungen:

Date Completed 25.02.2005

Date Revised 29.01.2022

published: Print-Electronic

Citation Status MEDLINE

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM151749280