Three ryanodine receptor isoforms exist in avian striated muscles

Abstract

Two isoforms of the ryanodine receptor (termed alpha and beta) are coexpressed in avian fast twitch skeletal muscle, whereas a single isoform is expressed in avian cardiac muscle. We have investigated the relationship between these three proteins, comparing several different properties. First, the three receptor isoform subunits have different mobilities on SDS-polyacrylamide gels. Second, monoclonal antibodies against the chicken skeletal muscle receptor isoforms recognize shared and unique epitopes in each receptor protein, indicating there is not a simple antigenic relationship between the isoforms. Third, the three receptor isoforms exhibit different susceptibilities to proteolysis by trypsin, and limited tryptic digestion yields a different peptide map for each isoform. Fourth, in native sarcoplasmic reticulum membranes, the chicken muscle receptor isoforms are phosphorylated to different extents by the multifunctional calcium/calmodulin-dependent protein kinase II (beta > cardiac > alpha). Fifth, the sites phosphorylated by the calcium/calmodulin-dependent protein kinase in the chicken cardiac and skeletal receptor isoforms are not equivalent. A polyclonal serum, produced against a synthetic peptide containing the site phosphorylated by this kinase in the mammalian cardiac muscle receptor, by immunoprecipitation showed markedly different avidities for the receptor isoforms, and recognized only the cardiac receptor isoform on Western blots. Sixth, the chicken ryanodine receptor isoforms differ in the extent to which they bind azido[125I]calmodulin (alpha > beta > cardiac). These results indicate that three distinct ryanodine receptor proteins are expressed in chicken striated muscles.

Characterization of the Calcium-release Channel/Ryanodine Receptor from Zebrafish Skeletal Muscle

“…In contrast to mammalian skeletal muscle, which expresses predominantly RyR1 and only small amounts of RyR3 (Takeshima et al 1994(Takeshima et al , 1995, nonmammalian vertebrate skeletal muscle tissue was found to express both isoforms together at equal amounts ( Fig. 1; Airey et al, 1990Airey et al, , 1993Olivares et al, 1991;Lai et al, 1992;O'Brien et al, 1993). This finding has been interpreted both as a phylogenetic specialization using a 2-component model of Ca 2+ release in skeletal muscle (O'Brien et al, 1995) and as a phylogenetic precursor form of the mammalian muscle types (Ottini et al, 1996).…”

“…Two types of functionally distinguishable RyRs were found, as in other teleosts (Block et al, 1994;O'Brien et al, 1995) and sauropsids O'Brien et al, 1995;Ottini et al, 1996). Ottini et al, 1996 could show that the homologues of the two isoforms in chicken, termed ␣ and ␤ isoform and identified based on biochemical and immunochemical properties (Airey et al, 1990(Airey et al, , 1993Olivares et al, 1991;Lai et al, 1992;O'Brien, Meissner & Block, 1993), are mammalian RyR1 and RyR3. In contrast to mammalian skeletal muscle, which expresses predominantly RyR1 and only small amounts of RyR3 (Takeshima et al 1994(Takeshima et al , 1995, nonmammalian vertebrate skeletal muscle tissue was found to express both isoforms together at equal amounts ( Fig.…”

Localization of Ryanodine Receptors in Smooth Muscle

“…This antibody has been shown to bind selectively to a variety of avian and mammalian RyR isoforms. 19 The reactivity of mAb110E for guinea pig RyR isoforms was determined by Western blotting. Homogenates of guinea pig aorta, ileum, cardiac muscle, and psoas muscle were size-fractionated by SDS-PAGE on 7.5% gels and transferred to PVDF membranes.…”

Calcium dependence of ryanodine‐sensitive calcium channels from brain cortex endoplasmic reticulum

“…Protein was determined according to Bradford [12]. Standard procedures were followed for SDS-PAGE gels and Western blot analysis of membrane fractions [13], using 2G6 anti-ryanodine-receptor antibody [14] kindly provided by Drs. J. Airey and J. Sutko.…”