ATP2B2
Description
The ATP2B2 (ATPase plasma membrane Ca2+ transporting 2) is a protein-coding gene located on chromosome 3.
Plasma membrane calcium-transporting ATPase 2 is an enzyme encoded by the ATP2B2 gene in humans. It belongs to the P-type primary ion transport ATPases, characterized by forming an aspartyl phosphate intermediate during the reaction cycle. These enzymes remove calcium ions from eukaryotic cells against large concentration gradients, playing a crucial role in intracellular calcium homeostasis. At least four separate genes encode mammalian plasma membrane calcium ATPase isoforms, with further diversity arising from alternative splicing of transcripts. The expression of different isoforms and splice variants is regulated in a tissue- and cell type-specific manner, suggesting adaptation to the physiological needs of specific cells and tissues. This gene encodes the plasma membrane calcium ATPase isoform 2. Alternative splicing generates different isoforms.
ATP2B2 acts as an ATP-driven calcium ion pump, maintaining basal intracellular calcium levels in specialized cells of the cerebellar circuit, vestibular and cochlear systems. It utilizes ATP to transport calcium ions from the cell's interior across the plasma membrane to the exterior. This pump exhibits rapid activation and calcium clearance rates, enabling it to control rapid neuronal calcium dynamics. At the parallel fiber to Purkinje neuron synapse, it mediates presynaptic calcium efflux in response to climbing fiber-induced calcium increases. This fast return of calcium concentrations to their resting levels contributes to long-term depression induction and motor learning. ATP2B2 is crucial for hearing and balance, transporting calcium ions from stereocilia to the endolymph in cochlear hair cells, thereby dissipating calcium transients generated by the opening of mechanoelectrical transduction channels. It also regulates calcium levels in the vestibular system, contributing to otoconia formation. In non-excitable cells, it regulates calcium signaling through spatial control of calcium extrusion and dissipation of calcium transients from store-operated channels. In the lactating mammary gland, ATP2B2 enables the high calcium content in milk.
ATP2B2 is also known as DFNA82, PMCA2, PMCA2a, PMCA2i.
