P-type calcium transporter activity

Definition

Target type: molecularfunction

Enables the transfer of a solute or solutes from one side of a membrane to the other according to the reaction: ATP + H2O + Ca2+(in) = ADP + phosphate + Ca2+(out). [RHEA:18105]

P-type calcium transporter activity is a molecular function characterized by the movement of calcium ions (Ca2+) across cellular membranes against their electrochemical gradient. This process is driven by the hydrolysis of ATP, hence the "P-type" designation, referring to phosphorylation of the transporter protein. These transporters play a critical role in maintaining calcium homeostasis within cells, a process vital for various cellular functions, including muscle contraction, neurotransmission, and cell signaling. The mechanism involves a series of steps: 1) Binding of calcium ions to the transporter's binding site on the intracellular side of the membrane. 2) Phosphorylation of the transporter by ATP, leading to a conformational change. 3) This conformational change exposes the calcium binding site to the extracellular side of the membrane, facilitating calcium release. 4) Dephosphorylation of the transporter restores the initial conformation, allowing for further cycles of calcium transport. P-type calcium transporters are found in a variety of tissues and cell types, with distinct isoforms exhibiting specific properties and functions. For example, the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) pumps calcium into the sarcoplasmic reticulum of muscle cells, essential for muscle relaxation. Conversely, plasma membrane Ca2+-ATPase (PMCA) pumps calcium out of the cell, contributing to calcium signal termination and maintaining low intracellular calcium levels. Overall, P-type calcium transporter activity is a fundamental molecular process that ensures proper calcium homeostasis, crucial for the intricate functioning of cells and organisms.'
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Proteins (6)

Compounds (7)