ATP2A1-3 transport cytosolic Ca2+ to dense tubular network lumen

Stable Identifier
R-HSA-418365
Type
Reaction
Species
Homo sapiens
Compartment
Synonyms
Sequestration of Ca2+ to dense tubular network lumen
Locations in the PathwayBrowser
Summation

Intracellular pools of Ca2+ serve as the source for inositol 1,4,5-trisphosphate (IP3) -induced alterations in cytoplasmic free Ca2+. In most human cells Ca2+ is stored in the lumen of the sarco/endoplastic reticulum by ATPases known as SERCAs (ATP2As). In platelets, ATP2As transport Ca2+ into the platelet dense tubular network. ATP2As are P-type ATPases, similar to the plasma membrane Na+ and Ca+-ATPases. Humans have three genes for SERCA pumps; ATP2A1-3. Studies on ATP2A1 suggest that it binds two Ca2+ ions from the cytoplasm and is subsequently phosphorylated at Asp351 before translocating Ca2+ into the SR lumen. There is a counter transport of two or possibly three protons ensuring partial charge balancing. Sarcolipin (SLN) can reversibly inhibit the activity of ATP2A1 by decreasing the apparent affinity of the ATPase for Ca2+ (Gorski et al. 2013) whereas activated Ca2+/CaM-dependent protein kinase II (CAMK2) and sorcin (SRI) can both stimulate ATP2A1-3 activity (Toyofuku et al. 1994, Matsumoto et al. 2005).

Participants
Participant Of
Catalyst Activity
Catalyst Activity
Title
calcium-transporting ATPase activity of ATP2A1-3 [platelet dense tubular network membrane]
Physical Entity
Activity
Orthologous Events