Domain

Calsequestrin, middle TRX-fold domain (IPR041858)

Short name: Calsequestrin_middle_dom

Overlapping homologous superfamilies

Domain relationships

None.

Description

Calsequestrin contains three redox inactive TRX-fold domains [PMID: 9628486, PMID: 22337878]. This entry represents the middle TRX-fold domain.

Calsequestrin is the principal calcium-binding protein present in the sarcoplasmic reticulum of cardiac and skeletal muscle [PMID: 3379055]. It is a highly acidic protein that is able to bind over 40 calcium ions and acts as an internal calcium store in muscle. Sequence analysis has suggested that calcium is not bound in distinct pockets via EF-hand motifs, but rather via presentation of a charged protein surface.

Two forms of calsequestrin have been identified. The cardiac form is present in cardiac and slow skeletal muscle and the fast skeletal form is found in fast skeletal muscle. The release of calsequestrin-bound calcium (through a a calcium release channel) triggers muscle contraction. The active protein is not highly structured, more than 50% of it adopting a random coil conformation [PMID: 3427023]. When calcium binds there is a structural change whereby the alpha-helical content of the protein increases from 3 to 11% [PMID: 3427023]. Both forms of calsequestrin are phosphorylated by casein kinase II, but the cardiac form is phosphorylated more rapidly and to a higher degree [PMID: 1985907].

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
CDD
  • cd03066 (PDI_b_Calsequestrin_middle)