CASQ1
Function
Calsequestrin is a high-capacity, moderate affinity, calcium-binding protein and thus acts as an internal calcium store in muscle (PubMed:28895244). Calcium ions are bound by clusters of acidic residues at the protein surface, often at the interface between subunits. Can bind around 80 Ca(2+) ions (PubMed:28895244). Regulates the release of lumenal Ca(2+) via the calcium release channel RYR1; this plays an important role in triggering muscle contraction. Negatively regulates store-operated Ca(2+) entry (SOCE) activity (PubMed:27185316).
Involvement in disease
Myopathy, vacuolar, with CASQ1 aggregates
VMCQA
An autosomal dominant mild muscle disorder characterized by adult onset of muscle cramping and weakness as well as increased levels of serum creatine kinase. The disorder is not progressive, and some patients may be asymptomatic.
None
The disease is caused by variants affecting the gene represented in this entry.
Myopathy, tubular aggregate, 1
TAM1
A rare congenital myopathy characterized by regular arrays of membrane tubules on muscle biopsies without additional histopathological hallmarks. Tubular aggregates in muscle are structures of variable appearance consisting of an outer tubule containing either one or more microtubule-like structures or amorphous material. They may occur in a variety of circumstances, including inherited myopathies, alcohol- and drug-induced myopathies, exercise-induced cramps or muscle weakness.
None
The disease is caused by variants affecting the gene represented in this entry.
Post-translational modifications
N-glycosylated.
Sequence Similarities
Belongs to the calsequestrin family.
Tissue Specificity
Expressed in myoblasts (at protein level).
Cellular localization
- Endoplasmic reticulum
- Sarcoplasmic reticulum
- Sarcoplasmic reticulum lumen
- Sarcoplasmic reticulum membrane
- Peripheral membrane protein
- Lumenal side
- Mitochondrion matrix
- This isoform of calsequestrin occurs in the sarcoplasmic reticulum's terminal cisternae luminal spaces of fast skeletal muscle cells. Preferentially forms linear and round aggregates in the endoplasmic reticulum (ER) of resting cells (PubMed:28895244). In a minority of cells, homogeneously detected in the ER lumen (PubMed:28895244). Colocalizes with STIM1 at endoplasmic reticulum in response to a depletion of intracellular calcium (PubMed:27185316).
Alternative names
CASQ, CASQ1, Calsequestrin-1, Calmitine