We have analyzed protein expression and enzyme activity of the sarcoplasmic reticulum Ca2+-transporting ATPase (SERCA) in horse gluteal muscle. Horses exhibit a high incidence of recurrent exertional rhabdomyolysis, with myosolic Ca2+ proposed, but yet to be established, as the underlying cause. To better assess Ca2+ regulatory mechanisms, we developed an improved protocol for isolating sarcoplasmic reticulum (SR) vesicles from horse skeletal muscle, based on mechanical homogenization and optimized parameters for differential centrifugation. Immunoblotting identified the peak subcellular fraction containing the SERCA1 protein (fast-twitch isoform). Gel analysis using the Stains-all dye demonstrated that calsequestrin (CASQ) and phospholipids are highly enriched in the SERCA-containing subcellular fraction isolated from horse gluteus. Immunoblotting also demonstrated that these horse SR vesicles show low content of glycogen phosphorylase (GP), which is likely an abundant contaminating protein of traditional horse SR preps. The maximal Ca2+-activated ATPase activity (Vmax) of SERCA in horse SR vesicles isolated using this protocol is 5‒25-fold greater than previously-reported SERCA activity in SR preps from horse skeletal muscle. We propose that this new protocol for isolating SR vesicles will be useful for determining enzymatic parameters of horse SERCA with high fidelity, plus assessing regulatory effect of SERCA peptide subunit(s) expressed in horse muscle.
Bibliographical noteFunding Information:
This study was supported in part by a Morris Animal Foundation grant to S.J.V., J.M.A., and D.D.T. [grant number D16EQ-004 ]. Morris Animal Foundation is the global leader in supporting science that advances animal health. This study was supported in part by National Institutes of Health grants to D.D.T. [grant numbers GM027906 , AG026160 , and HL139065 ]. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. The funding agencies had no role in study design, data collection, data analysis, decision to publish, or manuscript preparation.
© 2020 Elsevier Inc.
Copyright 2021 Elsevier B.V., All rights reserved.
- Equidae [B01.050.150.900.649.313.984.235]
- Gel electrophoresis
- Intracellular membranes [A11.284.835.514]
- Membrane-bound enzyme
- Muscle, Skeletal [A02.633.567]
- Rhabdomyolysis [C05.651.807]
- Sarcoplasmic reticulum calcium-transporting ATPases [D08.811.277.040.025.314.250.500]
- Western blotting [E05.601.470.320.200]
PubMed: MeSH publication types
- Journal Article
- Research Support, Non-U.S. Gov't
- Research Support, N.I.H., Extramural