Calreticulin

Calreticulin is a protein that in humans is encoded by the CALR gene. It is a multifunctional protein that binds Ca^2+ ions (calcium) and plays a significant role in protein folding and quality control in the endoplasmic reticulum (ER).

Structure

Calreticulin is a 46kDa protein resident in the lumen of the ER. The protein structure of calreticulin is divided into three distinct domains: the N-domain, P-domain, and C-domain. The N-domain is responsible for lectin-like chaperone activity, the P-domain for Ca^2+ binding, and the C-domain for interaction with other proteins.

Function

Calreticulin plays a crucial role in a variety of cellular processes. It is involved in the regulation of intracellular Ca^2+ homeostasis, protein folding and quality control, cell adhesion, and immune response modulation. It also has a role in cellular signaling, where it can influence gene expression and cell cycle progression.

Clinical significance

Mutations in the CALR gene have been associated with a variety of diseases, including myeloproliferative neoplasms, essential thrombocythemia, and primary myelofibrosis. Calreticulin can also be found in the extracellular matrix, where it can influence cell adhesion and migration, processes that are often dysregulated in cancer.

See also

• Endoplasmic reticulum
• Protein folding
• Calcium in biology
• Myeloproliferative neoplasm
• Essential thrombocythemia
• Primary myelofibrosis