Cerebrospinal fluid calcium homeostasis: evidence for a plasma membrane Ca2+-pump in mammalian choroid plexus.
A major unanswered question in central nervous system physiology concerns the mechanism by which cerebrospinal fluid (CSF) Ca2+ homeostasis is maintained in the face of hypo- or hypercalcemia. To address this question, we sought and found a protein of Mr approximately 140,000 in choroid plexus plasma membranes that forms a phosphorylated intermediate with characteristics of a plasma membrane Ca2+-pump. A choroid plexus plasma membrane protein of this molecular weight also bound to a monoclonal antibody prepared against the human erythrocyte plasma membrane Ca2+-Mg2+ ATPase Ca2+-pump. When this monoclonal antibody was used for immunohistochemical localization, the plasma membrane Ca2+-pump was found primarily in the CSF-facing membranes of choroid plexus cells from rats, cats, and man. The localization of a plasma membrane Ca2+-pump in the CSF-facing membranes of the choroid plexus suggests that the choroid plexus, by mechanisms including this pump, may regulate CSF Ca2+ concentrations.
Borke
J L
JL
Department of Medicine, Mayo Clinic and Foundation, Rochester, MN 55905.
Caride
A J
AJ
Yaksh
T L
TL
Penniston
J T
JT
Kumar
R
R
D000818:Animals; D000911:Antibodies, Monoclonal; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism*; D002118:Calcium / Q000134:cerebrospinal fluid*; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D002415:Cats; D002831:Choroid Plexus / Q000166:cytology / Q000378:metabolism*; D006706:Homeostasis; D007150:Immunohistochemistry; D008970:Molecular Weight
D000911:Antibodies, Monoclonal; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases; D002118:Calcium