Calsequestrin 1 Antibody [P19M13]

Application: Reactivity: Mouse, Rat, Human

Lane 1: Mouse muscle, Lane 2: Rat muscle

Usage Information

Dilution
WB1:10000 - 1:50000 IHC1:100 - 1:250

Application
WB, IHC

Reactivity
Mouse, Rat, Human

Source
Rabbit Monoclonal Antibody

Storage Buffer
PBS, pH 7.2+50% Glycerol+0.05% BSA+0.01% NaN3

Storage (from the date of receipt)
-20°C (avoid freeze-thaw cycles), 2 years

Predicted MW Observed MW
44 kDa 63 kDa
^*Why do the predicted and actual molecular weights differ? The following reasons may explain differences between the predicted and actual protein molecular weight.

Positive Control	Human skeletal muscle tissue; Rat muscle tissue; Mouse muscle tissue
Negative Control

Datasheet & SDS

Biological Description

Specificity
Calsequestrin 1 Antibody [P19M13] detects endogenous levels of total Calsequestrin 1 protein.

Clone
P19M13

Synonym(s)
CASQ, CASQ1, Calsequestrin-1, Calmitine

Background
Calsequestrin 1 (CASQ1) is the principal high-capacity, low-affinity Ca²⁺-binding protein in the sarcoplasmic reticulum (SR) terminal cisternae of fast-twitch skeletal muscle, crucial for enabling rapid Ca²⁺ release during muscle contraction while preventing calcium overload. CASQ1 is composed of three thioredoxin-like domains (I–III) formed by five-stranded β-sheets flanked by α-helices, and features flexible N- and C-terminal tails rich in aspartate and glutamate residues that create multiple Ca²⁺-binding pockets. At luminal Ca²⁺ concentrations around 1 mM, CASQ1 monomers polymerize through back-to-back C-terminal dimerization (mediated by Asp-rich CAS motifs binding 6–8 Ca²⁺ ions) and front-to-front N-terminal interactions stabilized by Glu55-Lys49 salt bridges, resulting in electronegative polymer networks capable of buffering up to 80 Ca²⁺ ions per molecule. These polymers compact further to accommodate higher Ca²⁺ loads and anchor to the ryanodine receptor (RyR1) via triadin and junctin, facilitating the close proximity needed for efficient Ca²⁺ release. CASQ1 polymerization allows massive storage of Ca²⁺ with low free [Ca²⁺] in the SR, protecting against osmotic stress, and serves as a dynamic sensor of luminal Ca²⁺: at high [Ca²⁺], polymer proximity inhibits RyR1 to preserve stores, while depolymerization upon release relieves inhibition to amplify excitation-contraction coupling. CASQ1 also modulates store-operated Ca²⁺ entry (SOCE) through reverse signaling with STIM1/2, coordinates reuptake by SERCA, and prevents Ca²⁺ depletion during muscle fatigue. Mutations in CASQ1 that impair its polymerization or anchoring disrupt SR Ca²⁺ handling, leading to pathological Ca²⁺ leaks, muscle weakness, and disorders such as malignant hyperthermia, environmental heat stroke, and tubular aggregate myopathy, which are characterized by fatal hypermetabolic crises.

Background

Calsequestrin 1 (CASQ1) is the principal high-capacity, low-affinity Ca²⁺-binding protein in the sarcoplasmic reticulum (SR) terminal cisternae of fast-twitch skeletal muscle, crucial for enabling rapid Ca²⁺ release during muscle contraction while preventing calcium overload. CASQ1 is composed of three thioredoxin-like domains (I–III) formed by five-stranded β-sheets flanked by α-helices, and features flexible N- and C-terminal tails rich in aspartate and glutamate residues that create multiple Ca²⁺-binding pockets. At luminal Ca²⁺ concentrations around 1 mM, CASQ1 monomers polymerize through back-to-back C-terminal dimerization (mediated by Asp-rich CAS motifs binding 6–8 Ca²⁺ ions) and front-to-front N-terminal interactions stabilized by Glu55-Lys49 salt bridges, resulting in electronegative polymer networks capable of buffering up to 80 Ca²⁺ ions per molecule. These polymers compact further to accommodate higher Ca²⁺ loads and anchor to the ryanodine receptor (RyR1) via triadin and junctin, facilitating the close proximity needed for efficient Ca²⁺ release. CASQ1 polymerization allows massive storage of Ca²⁺ with low free [Ca²⁺] in the SR, protecting against osmotic stress, and serves as a dynamic sensor of luminal Ca²⁺: at high [Ca²⁺], polymer proximity inhibits RyR1 to preserve stores, while depolymerization upon release relieves inhibition to amplify excitation-contraction coupling. CASQ1 also modulates store-operated Ca²⁺ entry (SOCE) through reverse signaling with STIM1/2, coordinates reuptake by SERCA, and prevents Ca²⁺ depletion during muscle fatigue. Mutations in CASQ1 that impair its polymerization or anchoring disrupt SR Ca²⁺ handling, leading to pathological Ca²⁺ leaks, muscle weakness, and disorders such as malignant hyperthermia, environmental heat stroke, and tubular aggregate myopathy, which are characterized by fatal hypermetabolic crises.

References
https://pubmed.ncbi.nlm.nih.gov/38136565/ https://pubmed.ncbi.nlm.nih.gov/33288873/

Reference Table for Selecting PVDF Membrane Pore Size Specifications

Protein Size (kDa)	PVDF Transfer Membrane Pore Size (μm)
< 10	0.22
10-20	0.22
20-30	0.45
30-45	0.45
45-70	0.45
80-100	0.45
100-140	0.45
> 140	0.45

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Protein Size (kDa)	Separating Gel Percentage
4-40	20%
12-45	15%
10-70	12.5%
15-100	10%
25-100	8%
60-210	5%