Structure and functional expression of an omega-conotoxin-sensitive human N-type calcium channel
| Autor: | Saraswathi Patthi, Ann F. McCue, Steven B. Ellis, Gonul Velicelebi, Daniel H. Feldman, Michael M. Harpold, Paul Brust, Susan Simerson, Azarnoush Maroufi, Mark E. Williams |
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| Rok vydání: | 1992 |
| Předmět: |
Male
Gi alpha subunit Molecular Sequence Data Biology N-type calcium channel Transfection Peptides Cyclic Cell Line Membrane Potentials SCN3A Neuroblastoma omega-Conotoxin GVIA Sequence Homology Nucleic Acid Humans Amino Acid Sequence G alpha subunit Multidisciplinary Calcium channel T-type calcium channel R-type calcium channel Biochemistry G12/G13 alpha subunits Biophysics Calcium Female Calcium Channels Sequence Alignment |
| Zdroj: | Science (New York, N.Y.). 257(5068) |
| ISSN: | 0036-8075 |
| Popis: | N-type calcium channels are omega-conotoxin (omega-CgTx)-sensitive, voltage-dependent ion channels involved in the control of neurotransmitter release from neurons. Multiple subtypes of voltage-dependent calcium channel complexes exist, and it is the alpha 1 subunit of the complex that forms the pore through which calcium enters the cell. The primary structures of human neuronal calcium channel alpha 1B subunits were deduced by the characterization of overlapping complementary DNAs. Two forms (alpha 1B-1 and alpha 1B-2) were identified in human neuroblastoma (IMR32) cells and in the central nervous system, but not in skeletal muscle or aorta tissues. The alpha 1B-1 subunit directs the recombinant expression of N-type calcium channel activity when it is transiently co-expressed with human neuronal beta 2 and alpha 2b subunits in mammalian HEK293 cells. The recombinant channel was irreversibly blocked by omega-CgTx but was insensitive to dihydropyridines. The alpha 1B-1 alpha 2b beta 2-transfected cells displayed a single class of saturable, high-affinity (dissociation constant = 55 pM) omega-CgTx binding sites. Co-expression of the beta 2 subunit was necessary for N-type channel activity, whereas the alpha 2b subunit appeared to modulate the expression of the channel. The heterogeneity of alpha 1B subunits, along with the heterogeneity of alpha 2 and beta subunits, is consistent with multiple, biophysically distinct N-type calcium channels. |
| Databáze: | OpenAIRE |
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