Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Hohaus, A; Poteser, M; Romanin, C; Klugbauer, N; Hofmann, F; Morano, I; Haase, H; Groschner, K.
Modulation of the smooth-muscle L-type Ca2+ channel alpha1 subunit (alpha1C-b) by the beta2a subunit: a peptide which inhibits binding of beta to the I-II linker of alpha1 induces functional uncoupling.
Biochem J. 2000; 348 Pt 3(36):657-665
Doi: 10.1042/0264-6021:3480657
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- Führende Autor*innen der Med Uni Graz
- Groschner Klaus
- Co-Autor*innen der Med Uni Graz
- Poteser Michael
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- Abstract:
- Modulation of the smooth-muscle Ca(2+) channel alpha1C-b subunit by the auxiliary beta2a subunit was studied in the HEK 293 (cell line from human embryonic kidney cells) expression system. In addition, we tested whether the alpha1-beta interaction in functional channels is sensitive to an 18-amino-acid synthetic peptide that corresponds to the sequence of the defined major interaction domain in the cytoplasmic I-II linker of alpha1C (AID-peptide). Ca(2+) channels derived by co-expression of alpha1C-b and beta2a subunits exhibited an about 3-fold higher open probability (P(o)) than alpha1C-b channels. High-P(o) gating of alpha1C-b.beta2a channels was associated with the occurrence of long-lasting channel openings [mean open time (tau)>10 ms] which were rarely observed in alpha1C-b channels. Modulation of fast gating by the beta2a subunit persisted in the cell-free, inside-out recording configuration. Biochemical experiments showed that the AID-peptide binds with appreciable affinity to beta2 subunits of native Ca(2+) channels. Binding of the beta2 protein to immobilized AID-peptide was specifically inhibited (K(i) of 100 nM) by preincubation with free (uncoupled) AID-peptide, but not by a corresponding scrambled peptide. Administration of the AID-peptide (10 microM) to the cytoplasmic side of inside-out patches induced a substantial reduction of P(o) of alpha1C-b.beta2a channels. The scrambled control peptide failed to affect alpha1C-b. beta2a channels, and the AID-peptide (10 microM) did not modify alpha1C-b channel function in the absence of expressed beta2a subunit. Our results demonstrate that the beta2a subunit controls fast gating of alpha1C-b channels, and suggest the alpha1-beta interaction domain in the cytoplasmic I-II linker of alpha1C (AID) as a possible target of modulation of the channel. Moreover, our data are consistent with a model of alpha1-beta interaction that is based on multiple interaction sites, including AID as a determinant of the affinity of the alpha1-beta interaction.
- Find related publications in this database (using NLM MeSH Indexing)
- Animals -
- Calcium Channels, L-Type - chemistry Calcium Channels, L-Type - metabolism
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- Cytoplasm - metabolism
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- Ion Channel Gating -
- Muscle, Smooth - metabolism
- Peptide Fragments - metabolism
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