| First Author | Gregg RG | Year | 1996 |
| Journal | Proc Natl Acad Sci U S A | Volume | 93 |
| Issue | 24 | Pages | 13961-6 |
| PubMed ID | 8943043 | Mgi Jnum | J:37052 |
| Mgi Id | MGI:84458 | Doi | 10.1073/pnas.93.24.13961 |
| Citation | Gregg RG, et al. (1996) Absence of the beta subunit (cchb1) of the skeletal muscle dihydropyridine receptor alters expression of the alpha 1 subunit and eliminates excitation-contraction coupling. Proc Natl Acad Sci U S A 93(24):13961-6 |
| abstractText | The multisubunit (alpha 1s, alpha 2/delta, beta 1, and gamma) skeletal muscle dihydropyridine receptor transduces transverse tubule membrane depolarization into release of Ca2+ from the sarcoplasmic reticulum, and also acts as an L-type Ca2+ channel. The alpha 1s subunit contains the voltage sensor and channel pore, the kinetics of which are modified by the other subunits. To determine the role of the beta 1 subunit in channel activity and excitation-contraction coupling we have used gene targeting to inactivate the beta 1 gene. beta 1-null mice die at birth from asphyxia. Electrical stimulation of beta 1-null muscle fails to induce twitches, however, contractures are induced by caffeine. In isolated beta 1-null myotubes, action potentials are normal, but fail to elicit a Ca2+ transient. L-type Ca2+ current is decreased 10- to 20-fold in the beta 1-null cells compared with littermate controls. Immunohistochemistry of cultured myotubes shows that not only is the beta 1 subunit absent, but the amount of alpha 1s in the membrane also is undetectable. In contrast, the beta 1 subunit is localized appropriately in dysgenic, mdg/mdg, (alpha 1s-null) cells. Therefore, the beta 1 subunit may not only play an important role in the transport/insertion of the alpha 1s subunit into the membrane, but may be vital for the targeting of the muscle dihydropyridine receptor complex to the transverse tubule/sarcoplasmic reticulum junction. |
