The secretory pathway Ca2+/Mn2+-ATPase 2 is a Golgi-localized pump with high affinity for Ca2+ ions.
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Vanoevelen J, Dode L, Van Baelen K, Fairclough RJ, Missiaen L, Raeymaekers L, Wuytack F
The secretory pathway Ca2+/Mn2+-ATPase 2 is a Golgi-localized pump with high affinity for Ca2+ ions.
J Biol Chem. 2005 Jun 17;280(24):22800-8. Epub 2005 Apr 14.
- PubMed ID
- 15831496 [ View in PubMed]
- Abstract
Accumulation of Ca(2+) into the Golgi apparatus is mediated by sarco(endo)plasmic reticulum Ca(2+)-ATPases (SERCAs) and by secretory pathway Ca(2+)-ATPases (SPCAs). Mammals and birds express in addition to the housekeeping SPCA1 (human gene name ATP2C1, cytogenetic position 3q22.1) a homologous SPCA2 isoform (human gene name ATP2C2, cytogenetic position 16q24.1). We show here that both genes present an identical exon/intron layout. We confirmed that hSPCA2 has the ability to transport Ca(2+), demonstrated its Mn(2+)-transporting activity, showed its Ca(2+)- and Mn(2+)-dependent phosphoprotein intermediate formation, and documented the insensitivity of these functional activities to thapsigargin inhibition. The mRNA encoding hSPCA2 showed a limited tissue expression pattern mainly confined to the gastrointestinal and respiratory tract, prostate, thyroid, salivary, and mammary glands. Immunocytochemical localization in human colon sections presented a typical apical juxtanuclear Golgi-like staining. The expression in COS-1 cells allowed the direct demonstration of (45)Ca(2+) (K(0.5) = 0.27 microm) or (54)Mn(2+) transport into an A23187-releasable compartment.