A β1 subunit associated with one or more isoforms of brain voltage-sensitive Na channels has previously been cloned, sequenced and expressed. Northern and Western blot analyses have suggested that homologues to this protein are expressed in skeletal muscle and heart. Here, reverse transcriptase-polymerase chain reaction (RT-PCR)/cloning reveals that transcripts encoding identical β1 subunit ORFs are expressed in adult rat brain, skeletal muscle and heart. Heterologous co-expression of β1 with brain (RIIA) and skeletal muscle (μ1) α subunits caused a stabilization of normal, rapidly inactivating (mode 1) gating relative to anomalous, non-inactivating (mode 2) states and a negative shift in steady state inactivation. Chromosome mapping of the β1 subunit showed a single locus (Scn1b) in mouse chromosome 71.8 cM (± 1.2 cM) distal to D19F11S1h and 0.9 cM (± 0.9 cM) proximal to Pkca. This locus is in the region of the mouse mutant "quivering," characterized by a variety of neurological disorders and muscle paralysis. A mutation in a single β1 subunit forming functional complexes with multiple Na channel isoforms could underlie these deficits.
|Original language||English (US)|
|Number of pages||7|
|Journal||Biochemical and Biophysical Research Communications|
|State||Published - Sep 15 1993|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology