Epitopes of the human erythrocyte Ca2+-Mg2+ ATPase pump in human osteoblast-like cell plasma membranes.
Human osteoblast-like cells were examined for the presence of the Ca2+-Mg2+ ATPase pump. The osteoblast-like cells had characteristic features of the osteoblast phenotype, including the presence of osteonectin, bone GLA protein, and type I collagen. The cells were able to mineralize matrix, their production of cAMP increased in response to PTH, and their alkaline phosphatase activity increased in response to 1,25-dihydroxyvitamin D3. Immunocytochemical staining of the osteoblast-like cells with a monoclonal antibody against human red cell Ca2+-Mg2+ ATPase demonstrated the presence of an epitope of the Ca2+-Mg2+ ATPase in these cells; staining of paraffin-embedded osteoblast-like cell sections demonstrated anti-Ca2+-Mg2+ ATPase staining only in cell plasma membranes. Western blot analysis of osteoblast-like cell homogenates showed that the monoclonal antibody to human erythrocyte Ca2+-Mg2+ ATPase bound to a major band at 140,000 mol wt, similar to the mol wt of known plasma membrane Ca2+-Mg2+ ATPases. The presence in the osteoblast-like cells of a Ca2+-Mg2+ ATPase similar to the human red cell calcium pump suggests that this enzyme may play a role in osteoblast intracellular calcium homeostasis.
Borke
J L
JL
Department of Medicine, Mayo Clinic, Rochester, Minnesota 55905.
Eriksen
E F
EF
Minami
J
J
Keeting
P
P
Mann
K G
KG
Penniston
J T
JT
Riggs
B L
BL
Kumar
R
R
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000469:Alkaline Phosphatase / Q000096:biosynthesis; D000911:Antibodies, Monoclonal; D015153:Blotting, Western; D017301:Ca(2+) Mg(2+)-ATPase / Q000032:analysis*; D002135:Calcium-Binding Proteins / Q000032:analysis; D000252:Calcium-Transporting ATPases / Q000032:analysis*; D002352:Carrier Proteins / Q000032:analysis; D002462:Cell Membrane / Q000201:enzymology; D000242:Cyclic AMP / Q000096:biosynthesis; D000939:Epitopes / Q000032:analysis; D004912:Erythrocytes / Q000201:enzymology*; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008875:Middle Aged; D010006:Osteoblasts / Q000201:enzymology*; D015675:Osteocalcin; D015676:Osteonectin; D010641:Phenotype
D000911:Antibodies, Monoclonal; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D000939:Epitopes; D015676:Osteonectin; D015675:Osteocalcin; D000242:Cyclic AMP; D000469:Alkaline Phosphatase; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases