kalmoduliinin

Kalmoduliinin, commonly known in English as calmodulin, is a small cytosolic calcium-binding messenger protein that plays a central role in calcium signaling across eukaryotic cells. The term kalmoduliinin appears in some languages as a transliteration of calmodulin. The protein is highly conserved, consisting of about 149 amino acids and a molecular weight of ~17 kilodaltons. It contains four EF-hand motifs that bind calcium ions with high affinity.

In its calcium-free form, kalmoduliinin is relatively flexible. Upon binding calcium, it undergoes a conformational change that enables it to interact with and regulate a wide range of target proteins, including Ca2+/calmodulin-dependent kinases (CaMKs), phosphatases, adenylyl cyclases, and various ion channels. Kalmoduliinin acts as a universal calcium sensor and regulator, translating fluctuations in intracellular Ca2+ into diverse cellular responses such as muscle contraction, neurotransmitter release, gene expression, and metabolic control.

Genetically, mammals harbor three CALM genes (CALM1, CALM2, CALM3) that encode calmodulin proteins and are expressed broadly across tissues. The protein is highly conserved in evolution and is found in most eukaryotes, reflecting its fundamental role in cellular regulation.

Clinical relevance: Mutations in CALM genes have been linked to inherited cardiac arrhythmias, including long QT syndrome and catecholaminergic polymorphic ventricular tachycardia, often due to altered calcium binding or impaired interaction with target proteins. Ongoing research continues to elucidate the full range of kalmoduliinin-related signaling pathways across cell types.