Primary Structure of the β Subunit of the DHP-Sensitive Calcium Channel from Skeletal Muscle

Abstract

Eur. J. Immunol. 17, 237 (1987

The β1‐subunit is essential for modulation by protein kinase C of an human and a non‐human L‐type Ca2+ channel

“…Template DNAs for synthesizing rabbit ct2/d; [4] and ]~1 [12][13] cRNAs were kindly provided by F. Hofmann and V. Flockerzi (Mtinich, Germany), cRNAs were synthesized in vitro using the mCAP TM mRNA Capping Kit (Stratagene, La Jolla, CA). Oocytes were microinjected with cRNAs, single or premixed in equimolar ratios.…”

Tissue-specific expression of calcium channels

“…The purified complex contains four proteins (Figure 2) (Flockerzi et al 1986, Hymel et al 1988, Nunoki et al 1989, Mundiiia-Weilenmann et al 1991. The primary sequences of these proteins have been deduced by cloning their corresponding cDNAs from rabbit skeletal muscle (Tanabe et al 1987, Ellis et al 1988, Ruth et al 1989, Jay et al 1990. By using these cDNAs as probes, different a, and 8 subunits have been cloned from heart, smooth muscle, endocrine, and neuronal cells.…”

“…The skeletal l3 subunit (CaBl) is an intracellularly located membrane protein consisting of 524 amino acids (Ruth et al 1989). Its deduced amino acid sequence contains stretches of heptad repeat structure that are characteristic for cytoskeletal proteins.…”

“…Their deduced amino acid sequences show an overall homology to CaBl of 71% (CaB2) and 66.6% (CaB3). Differential splicing of the primary transcript of CaBl results in at least four isoforms: CaBla-CaBld (Ruth et al 1989, Pragnell et al 199 1, Williams et al 1992a. CaBla is expressed in skeletal muscle whereas the other isofonns are expressed in brain.…”

Voltage-Gated Calcium Channels

“…The amino acid sequence is organized in four repeated domains (I-IV), which each contains six transmembrane segments (S1 -S6) and a (Takahashi et al 1987a), the intracellular b subunit has predicted a helices but no transmembrane segments (Fig. 2) (Ruth et al 1989), whereas the g subunit is a glycoprotein with four transmembrane segments ( Fig. 2) (Jay et al 1990).…”